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Phylogeny of Trigonotis in China—with a special reference to its nutlet morphology and plastid genome
Xue-Min Xu, Dan-Hui Liu, Shi-Xin Zhu, Zhen-Long Wang, Zhen Wei, Quan-Ru Liu
Plant Diversity    2023, 45 (04): 409-421.   DOI: 10.1016/j.pld.2023.03.004
Abstract44)      PDF (20880KB)(25)       Save
The genus Trigonotis comprises nearly 60 species mainly distributed in East and Southeast Asia. China has the largest number of Trigonotis species in the world, with a total of 44 species, of which 38 are endemic. Nutlet morphology is useful for the taxonomic delimitation of Trigonotis. However, there are still controversial circumscriptions of nutlet shape in some species. In previous studies, interspecies phylogenetic relationships were inferred using few DNA markers and very few taxa, which possibly led to erroneous or incomplete conclusions. In this study, the nutlet morphology of 39 Trigonotis taxa and the characteristics of 34 complete chloroplast genomes (29 taxa) were investigated and analyzed. Then, the phylogenetic relationships were discussed within this genus based on complete chloroplast genomes. To the best of our knowledge, this study is the first comprehensive analysis of nutlet morphology and complete chloroplast genome of Trigonotis. Based on nutlet morphology, Trigonotis can be divided into two groups: Group 1, hemispherical or oblique tetrahedron with carpopodiums, and Group 2, inverted tetrahedron without carpopodiums. The chloroplast genome of Trigonotis exhibited a typical quadripartite structure, including 84–86 protein-coding, 37 transfer RNA, and 8 ribosomal RNA genes, with a total length of 147,247–148,986 bp. Genes in the junctions were well conserved in Trigonotis, similar to those in other Boraginaceae s.str. species. Furthermore, Trigonotis chloroplast genomes showed relatively high diversity, with more conserved genic regions than intergenic regions; in addition, we detected 14 hot spots (Pi > 0.005) in non-coding regions. Phylogenetic analyses based on chloroplast genome data identified highly resolved relationships between Trigonotis species. Specifically, Trigonotis was divided into two clades with strong support: one clade included species with hemispherical or oblique tetrahedron nutlets with carpopodiums and bracts, whereas the other clade included species with inverted tetrahedron nutlets without carpopodiums or bracts. Our results may inform future taxonomic, phylogenetic, and evolutionary studies on Boraginaceae.
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The worldwide allometric relationship in anatomical structures for plant roots
Yue Zhang, Jing-Jing Cao, Qing-Pei Yang, Ming-Zuo Wu, Yong Zhao, De-Liang Kong
Plant Diversity    2023, 45 (06): 621-629.   DOI: 10.1016/j.pld.2023.05.002
Abstract38)      PDF (3345KB)(45)       Save
The cortex (i.e., absorptive tissue) and stele (transportive vascular tissue) are fundamental to the function of plant roots. Unraveling how these anatomical structures are assembled in absorptive roots is essential for our understanding of plant ecology, physiology, and plant responses to global environmental changes. In this review, we first compile a large data set on anatomical traits in absorptive roots, including cortex thickness and stele radius, across 698 observations and 512 species. Using this data set, we reveal a common root allometry in absorptive root structures, i.e., cortex thickness increases much faster than stele radius with increasing root diameter (hereafter, root allometry). Root allometry is further validated within and across plant growth forms (woody, grass, and liana species), mycorrhiza types (arbuscular mycorrhiza, ectomycorrhiza, and orchid mycorrhizas), phylogenetic gradients (from ferns to Orchidaceae), and environmental change scenarios (e.g., elevation of atmospheric CO2 concentration and nitrogen fertilization). These findings indicate that root allometry is common in plants. Importantly, root allometry varies greatly across species. We then summarize recent research on the mechanisms of root allometry and potential issues regarding these mechanisms. We further discuss ecological and evolutionary implications of root allometry. Finally, we propose several important research directions that should be pursued regarding root allometry.
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Phylogeny, character evolution, and classification of Selaginellaceae(lycophytes)
Xin-Mao Zhou, Li-Bing Zhang
Plant Diversity    2023, 45 (06): 630-684.   DOI: 10.1016/j.pld.2023.07.003
Abstract38)      PDF (48681KB)(38)       Save
Selaginella is the largest and most taxonomically complex genus in lycophytes. The fact that over 750 species are currently treated in a single genus makes Selaginellales/Selaginellaceae unique in pteridophytes. Here we assembled a dataset of six existing and newly sampled plastid and nuclear loci with a total of 684 accessions (74% increase of the earlier largest sampling) representing ca. 300 species to infer a new phylogeny. The evolution of 10 morphological characters is studied in the new phylogenetic context. Our major results include: (1) the nuclear and plastid phylogenies are congruent with each other and combined analysis well resolved and strongly supported the relationships of all but two major clades; (2) the Sinensis group is resolved as sister to S. subg. Pulviniella with strong support in two of the three analyses; (3) most morphological characters are highly homoplasious but some characters alone or combinations of characters well define the major clades in the family; and (4) an infrafamilial classification of Selaginellaceae is proposed and the currently defined Selaginella s.l. is split into seven subfamilies (corresponding to the current six subgenera + the Sinensis group) and 19 genera (the major diagnosable clades) with nine new species-poor genera. We support the conservation of Selaginella with a new type, S. flabellata, to minimize nomenclatural instability. We provide a key to subfamilies and genera, images illustrating their morphology, their morphological and geographical synopses, a list of constituent species, and necessary new combinations. This new classification will hopefully facilitate communication, promote further studies, and help conservation.
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Molecular phylogeny and inflorescence evolution of Prunus (Rosaceae) based on RAD-seq and genome skimming analyses
Na Su, Richard G.J. Hodel, Xi Wang, Jun-Ru Wang, Si-Yu Xie, Chao-Xia Gui, Ling Zhang, Zhao-Yang Chang, Liang Zhao, Daniel Potter, Jun Wen
Plant Diversity    2023, 45 (04): 397-408.   DOI: 10.1016/j.pld.2023.03.013
Abstract35)      PDF (8751KB)(48)       Save
Prunus is an economically important genus widely distributed in the temperate Northern Hemisphere. Previous studies on the genus using a variety of loci yielded conflicting phylogenetic hypotheses. Here, we generated nuclear reduced representation sequencing data and plastid genomes for 36 Prunus individuals and two outgroups. Both nuclear and plastome data recovered a well-resolved phylogeny. The species were divided into three main clades corresponding to their inflorescence types, - the racemose group, the solitary-flower group and the corymbose group - with the latter two sister to one another. Prunus was inferred to have diversified initially in the Late Cretaceous around 67.32 million years ago. The diversification of the three major clades began between the Paleocene and Miocene, suggesting that paleoclimatic events were an important driving force for Prunus diversification. Ancestral state reconstructions revealed that the most recent common ancestor of Prunus had racemose inflorescences, and the solitary-flower and corymb inflorescence types were derived by reduction of flower number and suppression of the rachis, respectively. We also tested the hybrid origin hypothesis of the racemose group proposed in previous studies. Prunus has undergone extensive hybridization events, although it is difficult to identify conclusively specific instances of hybridization when using SNP data, especially deep in the phylogeny. Our study provides well-resolved nuclear and plastid phylogenies of Prunus, reveals substantial cytonuclear discord at shallow scales, and sheds new light on inflorescence evolution in this economically important lineage.
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Endemic medicinal plant distribution correlated with stable climate, precipitation, and cultural diversity
Gang Feng, Ying-Jie Xiong, Hua-Yu Wei, Yao Li, Ling-Feng Mao
Plant Diversity    2023, 45 (04): 479-484.   DOI: 10.1016/j.pld.2022.09.007
Abstract30)      PDF (3512KB)(15)       Save
Medicinal plants provide crucial ecosystem services, especially in developing countries such as China, which harbors diverse endemic medicinal plant species with substantial cultural and economic value. Accordingly, understanding the patterns and drivers of medicinal plant distribution is critical. However, few studies have investigated the patterns and drivers of endemic medicinal plants distribution in China. Here, we linked endemic medicinal plants distribution with possible explanatory variables, i.e., paleoclimate change, contemporary climate, altitudinal range and ethnic minority human population size at the prefecture city level in China. Our results show that endemic medicinal plants are concentrated in southern China, especially in southwestern China. Notably, both endemic medicinal plant species richness and the ratio of endemic medicinal plant species richness are negatively associated with glacial-interglacial anomaly in temperature, and positively associated with contemporary precipitation and altitudinal range. In addition, we found that endemic medicinal plant species richness is positively associated with ethnic minority population sizes as well as its ratio to the overall population size. These findings suggest that the distribution of endemic medicinal plants is determined by multiple drivers. Furthermore, our findings stress that dramatic future climate changes and massive anthropogenic activities in southern China pose great challenges to the conservation of China's endemic medicinal plants.
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Intercontinental comparison of phylogenetic relatedness in introduced plants at the transition from naturalization to invasion: A case study on the floras of South Africa and China
Hong Qian
Plant Diversity    2023, 45 (04): 363-368.   DOI: 10.1016/j.pld.2023.02.003
Abstract28)      PDF (2632KB)(32)       Save
Invasive species may pose significant threats to biodiversity and ecosystem structure and functioning. The number of introduced species that have become invasive is substantial and is rapidly increasing. Identifying potentially invasive species and preventing their expansion are of critical importance in invasion ecology. Phylogenetic relatedness between invasive and native species has been used in predicting invasion success. Previous studies on the phylogenetic relatedness of plants at the transition from naturalization to invasion have shown mixed results, which may be because different methods were used in different studies. Here, I use the same method to analyze two comprehensive data sets from South Africa and China, using two phylogenetic metrics reflecting deep and shallow evolutionary histories, to address the question whether the probability of becoming invasive is higher for naturalized species distantly related to the native flora. My study suggests that the probability of becoming invasive is higher for naturalized species closely related to the native flora. The finding of my study is consistent with Darwin's preadaptation hypothesis.
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Late Oligocene fossil acorns and nuts of Quercus section Cyclobalanopsis from the Nanning Basin, Guangxi, South China
Xiao-Yan Liu, Han-Zhang Song, Xin-Kai Wu, Jia-Rong Hu, Wei-Ye Huang, Cheng Quan, Jian-Hua Jin
Plant Diversity    2023, 45 (04): 434-445.   DOI: 10.1016/j.pld.2022.08.002
Abstract27)      PDF (24647KB)(10)       Save
Quercus is the largest genus within the Fagaceae and has a rich fossil record. Most of the fossil material is attributed to the subgenus Quercus based on leaves, pollen or rarely acorns and nuts. Fossil records of Q. section Cyclobalanopsis characterized by ring-cupped acorns are relatively few and especially those described based on nuts are scant. In this study, we described four new species of Quercus section Cyclobalanopsis based on mummified acorns and nuts: Q. paleodisciformis X.Y. Liu et J.H. Jin sp. nov., Q. paleohui X.Y. Liu et J.H. Jin sp. nov., Q. nanningensis X.Y. Liu et J.H. Jin sp. nov. and Q. yongningensis X.Y. Liu et J.H. Jin sp. nov. These species closely resemble the extant species Q. disciformis, Q. hui, Q. kerrii, and Q. dinghuensis. The occurrence of Q. section Cyclobalanopsis in the Oligocene stratum of Guangxi, South China, suggests that the section has diversified within its extant distribution center since the Oligocene. By combining records from other areas, we propose that the section first appeared in the middle Eocene of East Asia (Sino-Japan), has diversified in situ with a few elements scattering into West Asia and southern Europe since the Oligocene and Pliocene, respectively, and finally became restricted in East Asia since the Pleistocene. This indicates that the section originated and diversified in East Asia, before spreading into West Asia no later than the Oligocene and into southern Europe by the Pliocene. Subsequently it disappeared from South Europe and West Asia due to the appearance of the (summer dry) Mediterranean climate and widespread cooling during the Pleistocene.
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Geographic patterns of taxonomic and phylogenetic β-diversity of angiosperm genera in regional floras across the world
Hong Qian, Shenhua Qian
Plant Diversity    2023, 45 (05): 491-500.   DOI: 10.1016/j.pld.2023.07.008
Abstract27)      PDF (13072KB)(31)       Save
Beta diversity (β-diversity) is the scalar between local (α) and regional (γ) diversity. Understanding geographic patterns of β-diversity is central to ecology, biogeography, and conservation biology. A full understanding of the origin and maintenance of geographic patterns of β-diversity requires exploring both taxonomic and phylogenetic β-diversity, as well as their respective turnover and nestedness components, and exploring phylogenetic β-diversity at different evolutionary depths. In this study, we explore and map geographic patterns of β-diversity for angiosperm genera in regional floras across the world. We examine both taxonomic and phylogenetic β-diversity and their constituent components, and both tip-weighted and basal-weighted phylogenetic β-diversity, and relate them to latitude. On the one hand, our study found that the global distribution of β-diversity is highly heterogeneous. This is the case for both taxonomic and phylogenetic β-diversity, and for both tip-weighted and basal-weighted phylogenetic β-diversity. On the other hand, our study found that there are highly consistent geographic patterns among different metrics of β-diversity. In most cases, metrics of β-diversity are negatively associated with latitude, particularly in the Northern Hemisphere. Different metrics of taxonomic β-diversity are strongly and positively correlated with their counterparts of phylogenetic β-diversity.
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Resolving a nearly 90-year-old enigma: The rare Fagus chienii is conspecific with F. hayatae based on molecular and morphological evidence
Dan-Qi Li, Lu Jiang, Hua Liang, Da-Hai Zhu, Deng-Mei Fan, Yi-Xuan Kou, Yi Yang, Zhi-Yong Zhang
Plant Diversity    2023, 45 (05): 544-551.   DOI: 10.1016/j.pld.2023.01.003
Abstract25)      PDF (6334KB)(15)       Save
Taxonomic uncertainties of rare species often hinder effective prioritization for conservation. One such taxonomic uncertainty is the 90-year-old enigma of Fagus chienii. F. chienii was previously only known from the type specimens collected in 1935 in Pingwu County of Sichuan Province, China, and has long been thought to be on the verge of extinction. However, morphological similarities to closely related Fagus species have led many to question the taxonomic status of F. chienii. To clarify this taxonomic uncertainty, we used the newly collected samples to reconstruct a molecular phylogeny of Chinese Fagus species against the phylogenetic backbone of the whole genus using seven nuclear genes. In addition, we examined nine morphological characters to determine whether F. chienii is morphologically distinct from its putatively closest relatives (F. hayatae, F. longipetiolata, and F. lucida). Both morphological and phylogenetic analyses indicated that F. chienii is conspecific with F. hayatae. We recommended that F. chienii should not be treated as a separate species in conservation management. However, conservation strategies such as in situ protection and ex situ germplasm preservation should be adopted to prevent the peculiar “F. chienii” population from extinction.
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Parasite-host network analysis provides insights into the evolution of two mistletoe lineages (Loranthaceae and Santalaceae)
Jin Zhao, Yuanjie Li, Xuanni Wang, Manru Li, Wenbin Yu, Jin Chen, Ling Zhang
Plant Diversity    2023, 45 (06): 702-711.   DOI: 10.1016/j.pld.2023.03.008
Abstract25)      PDF (4618KB)(24)       Save
Mistletoes are ecologically important parasitic plants, with > 1600 species from five lineages worldwide. Mistletoe lineages exhibit distinct patterns of species diversification and host specificity, however, the mechanisms underlying these differences are poorly understood. In this study, we analysed a comprehensive parasite–host network, including 280 host species from 60 families and 22 mistletoe species from two lineages (Santalaceae and Loranthaceae) in Xishuangbanna, located in a biodiversity hotspot of tropical Asia. We identified the factors that predict the infection strength of mistletoes. We also detected host specificity and the phylogenetic signal of mistletoes and their hosts. We found that this interaction network could be largely explained by a model based on the relative abundance of species. Host infection was positively correlated with diameter at breast height and tree coverage, but negatively correlated with wood density. Overall, closely related mistletoe species tend to interact more often with similar hosts. However, the two lineages showed a significantly different network pattern. Rates of host generality were higher in Loranthaceae than in Santalaceae, although neither lineage showed phylogenetic signal for host generality. This study demonstrates that the neutral interaction hypothesis provides suitable predictions of the mistletoe–host interaction network, and mistletoe species show significant phylogenetic signals for their hosts. Our findings also indicate that high species diversification in Loranthaceae may be explained by high rates of host generality and the evolutionary history shared by Loranthaceae species with diverse host plants in the tropics.
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Does pollinator dependence decrease along elevational gradients?
Yue-Wen Xu, Lu Sun, Rong Ma, Yong-Qian Gao, Hang Sun, Bo Song
Plant Diversity    2023, 45 (04): 446-455.   DOI: 10.1016/j.pld.2023.03.006
Abstract25)      PDF (3232KB)(17)       Save
Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments. However, recent research has yet to consistently support the generality of this expectation. In this study, we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits. To answer these questions, we quantified pollinator–plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient (990–4260 m a.s.l.) in the Qinghai-Tibet Plateau. We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production (76.2% of seed production was contributed by animal pollinators and 44.6% of plants would produce no seed without pollinator visitation). Contrary to our expectation, there was no significant elevational gradient in pollinator dependence index. Although the pollinator dependence index was not significantly correlated with pollen limitation, flower size, floral longevity, or reward type, it was correlated with compatibility status and flowering time. These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau. Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region, particularly for early-flowering or self-incompatible plants growing at higher elevations (e.g., subnival belt).
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Mitochondrial RNA editing sites affect the phylogenetic reconstruction of gymnosperms
Shan-Shan Dong, Xu-Ping Zhou, Tao Peng, Yang Liu
Plant Diversity    2023, 45 (04): 485-489.   DOI: 10.1016/j.pld.2023.02.004
Abstract25)      PDF (3571KB)(18)       Save
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Forest characteristics, population structure and growth trends of threatened relict Pseudotsuga forrestii in China
Cindy Q. Tang, Shi-Qian Yao, Peng-Bin Han, Jian-Ran Wen, Shuaifeng Li, Ming-Chun Peng, Chong-Yun Wang, Tetsuya Matsui, Yong-Ping Li, Shan Lu, Yuan He
Plant Diversity    2023, 45 (04): 422-433.   DOI: 10.1016/j.pld.2022.10.005
Abstract24)      PDF (8499KB)(22)       Save
Pseudotsuga forrestii is a relict evergreen coniferous tree species in Pinaceae endemic to China. P. forrestii tree numbers have greatly decreased due to deforestation, over-utilization and habitat degradation. Here we clarify P. forrestii community types, structure, species diversity, seedling recruitments and growth trends. We identified four P. forrestii community types: (1) Pseudotsuga forrestii - Quercus guyavifolia - Acer davidii evergreen coniferous and broad-leaved mixed forest; (2) Pseudotsuga forrestii - Pinus yunnanensis - Quercus guyavifolia evergreen coniferous and broad-leaved mixed forest; (3) Pseudotsuga forrestii evergreen coniferous forest; (4) Pseudotsuga forrestii - Abies georgei var. smithii evergreen coniferous forest. P. forrestii forests are characterized by both warm temperate and temperate affinities. Simpson diversity, Pielou evenness, Shannon–Wiener diversity indices ranged from 0.75 to 0.76, 0.74–0.81, and 1.62–1.93, respectively, with no significant differences among the four forest types. The forest stratification was multilayered. The canopy layer was generally 10–25 m tall, with the emergent layer reached 25–42 m. DBH and age structures of P. forrestii showed multimodal distributions. Its maximum age P. forrestii was 570 years with a DBH of 143 cm. The growth of annual ring width of P. forrestii was slow, and generally decreased with age, whereas the basal area at the breast height increased with age. Established seedlings/saplings were mainly found in unstable micro-habitats. Regeneration of P. forrestii depends on moderate natural disturbances. Finally, we provide recommendations for P. forrestii conservation.
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New patterns of the tree beta diversity and its determinants in the largest savanna and wetland biomes of South America
Karla J.P. Silva-Souza, Maíra G. Pivato, Vinícius C. Silva, Ricardo F. Haidar, Alexandre F. Souza
Plant Diversity    2023, 45 (04): 369-384.   DOI: 10.1016/j.pld.2022.09.006
Abstract22)      PDF (16022KB)(12)       Save
Clear and data-driven bioregionalizations can provide a framework to test hypotheses and base biodiversity conservation. Here we used occurrence and abundance data in combination with objective analytical methods to propose two bioregionalization schemes for tree species of the Cerrado and the Pantanal in South America. We also evaluated the contribution of three sets of determinants of the occurrence- and abundance-based subregions. We compiled data on tree species composition from 894 local assemblages based on species occurrences, and from 658 local assemblages based on species abundances. We used an unconstrained community-level modelling approach and clustering techniques to identify and map tree subregions for the occurrence and the abundance data sets, separately. Hierarchical clustering analyses were conducted to investigate floristic affinities between the subregions and to map broader floristic regions. We used multinomial logistic regression models, deviance partitioning, and rank-sum tests to assess the main subregion correlates. We identified 18 occurrence- and four abundance-based subregions in the Cerrado-Pantanal. The hierarchical classifications grouped the occurrence-based subregions into nine floristic zones and abundance-based subregions into two broad floristic zones. Variation in subregions were explained mainly by environmental factors and spatial structure in both occurrence and abundance data sets. The occurrence- and abundance-based subregions are complementary approaches to disentangle macroecological patterns and to plan conservation efforts in the Cerrado and the Pantanal. Our findings based on occurrence data revealed more complex and interdigitated boundaries between subregions of tree species than previously reported. The environment, historical stability, and human effects act in a synergetic way on the distribution of the subregions. Finally, the relevance of contemporary environmental factors to the subregion patterns we found alert us to the profound impact global warming may have on the spatial organization of the Cerrado-Pantanal tree flora.
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Plastid phylogenomics and species discrimination in the “Chinese” clade of Roscoea (Zingiberaceae)
Hai-Su Hu, Jiu-Yang Mao, Xue Wang, Yu-Ze Liang, Bei Jiang, De-Quan Zhang
Plant Diversity    2023, 45 (05): 523-534.   DOI: 10.1016/j.pld.2023.03.012
Abstract22)      PDF (18700KB)(20)       Save
Roscoea is an alpine or subalpine genus from the pan-tropical family Zingiberaceae, which consists of two disjunct groups in geography, namely the “Chinese” clade and the “Himalayan” clade. Despite extensive research on the genus, Roscoea species remain poorly defined and relationships between these species are not well resolved. In this study, we used plastid genomes of nine species and one variety to resolve phylogenetic relationships within the “Chinese” clade of Roscoea and as DNA super barcodes for species discrimination. We found that Roscoea plastid genomes ranged in length from 163,063 to 163,796 bp, and encoded 113 genes, including 79 protein-coding genes, 30 tRNA genes, four rRNA genes. In addition, expansion and contraction of the IR regions showed obvious infraspecific conservatism and interspecific differentiation. Plastid phylogenomics revealed that species belonging to the “Chinese” clade of Roscoea can be divided into four distinct subclades. Furthermore, our analysis supported the independence of R. cautleoides var. pubescens, the recovery of Roscoea pubescens Z.Y. Zhu, and a close relationship between R. humeana and R. cautloides. When we used the plastid genome as a super barcode, we found that it possessed strong discriminatory power (90%) with high support values. Intergenic regions provided similar resolution, which was much better than that of protein-coding regions, hypervariable regions, and DNA universal barcodes. However, plastid genomes could not completely resolve Roscoea phylogeny or definitively discriminate species. These limitations are likely related to the complex history of Roscoea speciation, poorly defined species within the genus, and the maternal inheritance of plastid genomes.
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Drivers of the differentiation between broad-leaved trees and shrubs in the shift from evergreen to deciduous leaf habit in forests of eastern Asian subtropics
Yi Jin, Hong Qian
Plant Diversity    2023, 45 (05): 535-543.   DOI: 10.1016/j.pld.2022.12.008
Abstract21)      PDF (1032KB)(12)       Save
In eastern Asian subtropical forests, leaf habit shifts from evergreen to deciduous broad-leaved woody plants toward higher latitudes. This shift has been largely explained by the greater capacity of deciduous broad-leaved plants to respond to harsh climatic conditions (e.g., greater seasonality). The advantages of deciduous leaf habit over evergreen leaf habit in more seasonal climates have led us to hypothesize that leaf habits would shift in response to climate changes more conspicuously in forest canopy trees than in forest understory shrubs. Furthermore, we hypothesize that in the forests of the subtropics, plants at higher latitudes, regardless of growth form, would better tolerate seasonal harsh climates, and hence show less differentiation in leaf habit shift, compared to those at lower latitudes. To test these two hypotheses, we modelled the proportion of deciduous broad-leaved species and the incidence of deciduous and evergreen broad-leaved species in woody angiosperm species compositions of ten large-sized forest plots distributed in the Chinese subtropics. We found that the rate of leaf habit shift along a latitudinal gradient was higher in forest trees than in forest shrubs. We also found that the differentiation in leaf habit shift between trees and shrubs is greater at lower latitudes (i.e., warmer climates) than at higher latitudes (i.e., colder climates). These findings indicate that specialized forest plants are differentially affected by climate in distinct forest strata in a manner dependent on latitudinal distribution. These differences in forest plant response to changes in climate suggest that global climate warming will alter growth forms and geographical distributions and ranges of forests.
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RAD-sequencing improves the genetic characterization of a threatened tree peony (Paeonia ludlowii) endemic to China: Implications for conservation
Yu-Juan Zhao, Gen-Shen Yin, Xun Gong
Plant Diversity    2023, 45 (05): 513-522.   DOI: 10.1016/j.pld.2022.07.002
Abstract21)      PDF (2357KB)(11)       Save
Compared with traditional genetic markers, genomic approaches have proved valuable to the conservation of endangered species. Paeonia ludlowii having rarely and pure yellow flowers, is one of the world's most famous tree peonies. However, only several wild populations remain in the Yarlung Zangbo Valley (Nyingchi and Shannan regions, Xizang) in China due to increasing anthropogenic impact on the natural habitats. We used genome-wide single nucleotide polymorphisms to elucidate the spatial pattern of genetic variation, population structure and demographic history of P. ludlowii from the fragmented region comprising the entire range of this species, aiming to provide a basis for conserving the genetic resources of this species. Unlike genetic uniformity among populations revealed in previous studies, we found low but varied levels of intra-population genetic diversity, in which lower genetic diversity was detected in the population in Shannan region compared to those in Nyingzhi region. These spatial patterns may be likely associated with different population sizes caused by micro-environment differences in these two regions. Additionally, low genetic differentiation among populations (Fst = 0.0037) were detected at the species level. This line of evidence, combined with the result of significant genetic differentiation between the two closest populations and lack of isolation by distance, suggested that shared ancestry among now remnant populations rather than contemporary genetic connectivity resulted in subtle population structure. Demographic inference suggested that P. ludlowii probably experienced a temporal history of sharp population decline during the period of Last Glacial Maximum, and a subsequent bottleneck event resulting from prehistoric human activities on the Qinghai-Tibet Plateau. All these events, together with current habitat fragment and excavation might contribute to the endangered status of P. ludlowii. Our study improved the genetic characterization of the endangered tree peony (P. ludlowii) in China, and these genetic inferences should be considered when making different in situ and ex situ conservation actions for P. ludlowii in this evolutionary hotspot region.
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Integrative analysis of the metabolome and transcriptome reveals the potential mechanism of fruit flavor formation in wild hawthorn (Crataegus chungtienensis)
Xien Wu, Dengli Luo, Yingmin Zhang, Ling Jin, M. James C. Crabbe, Qin Qiao, Guodong Li, Ticao Zhang
Plant Diversity    2023, 45 (05): 590-600.   DOI: 10.1016/j.pld.2023.02.001
Abstract21)      PDF (10183KB)(6)       Save
Hawthorns are important medicinal and edible plants with a long history of health protection in China. Besides cultivated hawthorn, other wild hawthorns may also have excellent medicinal and edible value, such as Crataegus chungtienensis, an endemic species distributed in the Southwest of China. In this study, by integrating the flavor-related metabolome and transcriptome data of the ripening fruit of C. chungtienensis, we have developed an understanding of the formation of hawthorn fruit quality. The results show that a total of 849 metabolites were detected in the young and mature fruit of C. chungtienensis, of which flavonoids were the most detected metabolites. Among the differentially accumulated metabolites, stachyose, maltotetraose and cis-aconitic acid were significantly increased during fruit ripening, and these may be important metabolites affecting fruit flavor change. Moreover, several flavonoids and terpenoids were reduced after fruit ripening compared with young fruit. Therefore, using the unripe fruit of C. chungtienensis may allow us to obtain more medicinal active ingredients such as flavonoids and terpenoids. Furthermore, we screened out some differentially expressed genes (DEGs) related to fruit quality formation, which had important relationships with differentially accumulated sugars, acids, flavonoids and terpenoids. Our study provides new insights into flavor formation in wild hawthorn during fruit development and ripening, and at the same time this study lays the foundation for the improvement of hawthorn fruit flavor.
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Convergent relationships between flower economics and hydraulic traits across aquatic and terrestrial herbaceous plants
Yan Ke, Feng-Ping Zhang, Yun-Bing Zhang, Wei Li, Qin Wang, Da Yang, Jiao-Lin Zhang, Kun-Fang Cao
Plant Diversity    2023, 45 (05): 601-610.   DOI: 10.1016/j.pld.2023.01.006
Abstract21)      PDF (7920KB)(9)       Save
Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance. Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorly understood. Here, we hypothesize that the coordination and trade-offs between floral hydraulics and economics traits are independent of environmental conditions. To test this hypothesis, we investigated a total of 27 flower economics and hydraulic traits in six aquatic and six terrestrial herbaceous species grown in a tropical botanical garden. We found that although there were a few significant differences, most flower hydraulics and economics traits did not differ significantly between aquatic and terrestrial herbaceous plants. Both flower mass per area and floral longevity were significantly positively correlated with the time required for drying full-hydrated flowers to 70% relative water content. Flower dry matter content was strongly and positively related to drought tolerance of the flowers as indicated by flower water potential at the turgor loss point. In addition, there was a trade-off between hydraulic efficiency and the construction cost of a flower across species. Our results show that flowers of aquatic and terrestrial plants follow the same economics spectrum pattern. These results suggest a convergent flower economics design across terrestrial and aquatic plants, providing new insights into the mechanisms by which floral organs adapt to aquatic and terrestrial habitats.
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Soil water content and nitrogen differentially correlate with multidimensional leaf traits of two temperate broadleaf species
Ming-Yue Jin, Daniel J. Johnson, Guang-Ze Jin, Qing-Xi Guo, Zhi-Li Liu
Plant Diversity    2023, 45 (06): 694-701.   DOI: 10.1016/j.pld.2023.03.001
Abstract21)      PDF (4220KB)(17)       Save
The variation and correlation of leaf economics and vein traits are crucial for predicting plant ecological strategies under different environmental changes. However, correlations between these two suites of traits and abiotic factors such as soil water and nitrogen content remain ambiguous. We measured leaf economics and vein traits as well as soil water and nitrogen content for two different shade-tolerant species (Betula platyphylla and Acer mono) in four mixed broadleaved-Korean pine (Pinus koraiensis) forests along a latitudinal gradient in Northeast China. We found that leaf economics traits and vein traits were decoupled in shade-intolerant species, Betula platphylla, but significantly coupled in a shade-tolerant species, A. mono. We found stronger correlations among leaf traits in the shade tolerant species than in the shade intolerant species. Furthermore, leaf economic traits were positively correlated with the soil water gradient for both species, whereas vein traits were positively correlated with soil water gradient for the shade intolerant species but negatively correlated in the shade tolerant species. Although economic traits were positively correlated with soil nitrogen gradient in shade intolerant species but not correlated in shade tolerant species, vein traits were negatively correlated with soil nitrogen gradient in shade tolerant species but not correlated in shade intolerant species. Our study provides evidence for distinct correlations between leaf economics and vein traits and local abiotic factors of species differing in light demands. We recommend that the ecological significance of shade tolerance be considered for species when evaluating ecosystem functions and predicting plant responses to environmental changes.
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Germplasm resources and genetic improvement of Akebia: A new fruit crop in China
Shuai-Yu Zou, Chen Feng, Pu-Xin Gao, Tong-Jian Li, Tian-Jiao Jia, Hongwen Huang
Plant Diversity    2023, 45 (06): 712-721.   DOI: 10.1016/j.pld.2022.12.001
Abstract20)      PDF (24043KB)(9)       Save
Akebia species, belonging to Lardizabalaceae, are widespread from subtropical to temperate environments of China, Japan, and Korea. All known Akebia species have medicinal and dietary value and have been widely cultivated as a new fruit crop in many areas of China. However, compared with other crop species, the breeding improvement and commercial cultivation of Akebia remain in their infancy. This review systematically introduces the present germplasm resources, geographical distribution, biological characteristics, interspecific and intraspecific cross compatibility, molecular biology, and breeding progress in Akebia species. Akebia plants are widely distributed in Shanxi, Henan, Sichuan, Chongqing, Hunan, Hubei, Jiangxi, Zhejiang, and Fujian provinces of China, and wild Akebia plants exhibit abundant phenotypic and genetic diversity due to their wide range of geographical distribution and high adaptability in different habitats. Interspecific artificial hybridization experiments have been conducted in our Akebia germplasm resources nursery. The results showed that there was no reproductive isolation between Akebia species, and fertile progeny could be produced. The synthesis of knowledge on these species provides insights for the rational development and utilization of these germplasm resources, and can facilitate the development of new breeding lines or varieties for commercial cultivation or production. Finally, perspectives on Akebia breeding research are discussed and conclusions are provided. This review provided breeders with new insights into Akebia domestication and breeding, and we also proposed five basic steps in the domestication of new fruit crops.
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Functional diversity in an Andean subpáramo affected by wildfire in Colombia
Korina Ocampo-Zuleta, Ángela Parrado-Rosselli
Plant Diversity    2023, 45 (04): 385-396.   DOI: 10.1016/j.pld.2022.11.007
Abstract20)      PDF (4442KB)(5)       Save
Recently, the Andean subpáramo in Colombia has experienced severe wildfires, but little is known about the functional composition of recovering or not after a wildfire. Therefore, we examined the functional community composition subpáramo affected by fire in 2016. We documented how functional traits changed 31 months after the disturbance and compared them with an unburned site. We sampled from one to two years after the fire every four months, then registered all recruits in 16 5×5m plots. New individuals were classified into strategy functional groups based on the traits of persistence and dispersal. The first group was stem type and regeneration mechanism (seedling and resprout), and the second was fruit type and dispersal mode. We investigated the degree to which functional diversity changes plant communities over time (woody and non-woody), and we compared it with an unburned site. The most relevant results showed that resprouts and seed regenerated increased post-fire time and significant differences between sampling periods. The anemochory is the most relevant dispersal mode that indicates the community capacity to colonize the new gaps opened by the fire rapidly. We discuss how wildfire appears to be a triggering factor for persistence and dispersal strategy groups in subpáramo burned given their characteristics of tolerance to stress. For this reason, a greater functional divergence between the ecosystems studied post-fire recovery has been related to higher levels of biodiversity at the landscape scale due to the high degree of endemism and significant differences in species composition between páramos.
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The molecular mechanism of WRINKLED1 transcription factor regulating oil accumulation in developing seeds of castor bean
Qing Tan, Bing Han, Mohammad Enamul Haque, Ye-Lan Li, Yue Wang, Di Wu, Shi-Bo Wu, Ai-Zhong Liu
Plant Diversity    2023, 45 (04): 469-478.   DOI: 10.1016/j.pld.2022.09.003
Abstract20)      PDF (8011KB)(8)       Save
The transcription factor WRINKLED1 (WRI1), a member of AP2 gene family that contain typical AP2 domains, has been considered as a master regulator regulating oil biosynthesis in oilseeds. However, the regulatory mechanism of RcWRI1 in regulating oil accumulation during seed development has not been clearly addressed. Castor bean (Ricinus communis) is one of the most important non-edible oil crops and its seed oils are rich in hydroxy fatty acids, widely applied in industry. In this study, based on castor bean reference genome, three RcWRIs genes (RcWRI1, RcWRI2 and RcWRI3) were identified and the expressed association of RcWRI1 with oil accumulation were determined. Heterologous transformation of RcWRI1 significantly increased oil content in tobacco leaf, confirming that RcWRI1 activate lipid biosynthesis pathway. Using DNA Affinity Purification sequencing (DAP-seq) technology, we confirmed RcWRI1 binding with Transcription Start Site of genes and identified 7961 WRI1-binding candidate genes. Functionally, these identified genes were mainly involved in diverse metabolism pathways (including lipid biosynthesis). Three cis-elements AW-box ([CnTnG](n)7[CG]) and AW-boxes like ([GnAnC](n)6[GC]/[GnAnC](n)7[G]) bound with RcWRI1 were identified. Co-expression network analysis of RcWRI1 further found that RcWRI1 might be widely involved in biosynthesis of storage materials during seed development. In particular, yeast one hybrid experiments found that both AP2 domains within RcWRI1 were required in binding targeted genes. These results not only provide new evidence to understand the regulatory mechanism of RcWRI1 in regulation of oil accumulation during castor bean seed development, but also give candidate gene resource for subsequent genetic improvement toward increasing oil content in oilseed crops.
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The complete plastid genome provides insight into maternal plastid inheritance mode of the living fossil plant Ginkgo biloba
Mengxue Feng, Hanghui Kong, Meixiu Lin, Rongjing Zhang, Wei Gong
Plant Diversity    2023, 45 (06): 752-756.   DOI: 10.1016/j.pld.2023.09.001
Abstract19)      PDF (462KB)(12)       Save
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Is intraspecific trait differentiation in Parthenium hysterophorus a consequence of hereditary factors and/or phenotypic plasticity?
Amarpreet Kaur, Shalinder Kaur, Harminder Pal Singh, Daizy R. Batish
Plant Diversity    2023, 45 (05): 611-620.   DOI: 10.1016/j.pld.2022.09.002
Abstract18)      PDF (7849KB)(12)       Save
Of the various strategies adopted by an invasive plant species for expanding its niche breadth, phenotypic differentiation (either due to plasticity and/or adaptive evolution) is proven to be the most successful. Lately, we studied the persistence of substantial morpho-functional variations within the individuals of alien invasive plant, Parthenium hysterophorus in Chandigarh, India, through field surveys. Based on observed differences, the individuals were categorized into two morphotypes, PA and PB. PA had higher leaf area, leaf biomass, and chlorophyll content as compared with PB. However, PB had a higher stem circumference, stem specific density, twig dry matter content, profuse branching, bigger canopy, and better reproductive output than PA. To substantiate the persistence of intraspecific variations in P. hysterophorus and to deduce the possible genesis of these variations, we propagated both the morphotypes under experimental conditions in winter and summer. Apart from the key morpho-functional differences observed during the field studies, protein and carbohydrate metabolism were studied in leaves and roots of the propagated plants. Differences in plant metabolism were observed only during the early growth period, whereas the morpho-functional traits varied in the mature flowering plants. The effect of growth season was highly significant on all the studied morpho-functional and biochemical parameters (p ≤ 0.05). Parent morphotypes (P) and interactions between morphotypes and seasons significantly affected several growth parameters (p ≤ 0.05). The analyses revealed that the contrasting growth conditions at the time of transplantation and early growth may regulate the phenotype of P. hysterophorus. The pattern of intraspecific variations observed during the study is justified to consider morphotype PA as winter biotype and morphotype PB as summer biotype of P. hysterophorus. The study points towards the role of plasticity or a combination of genetic and environmental (G×E) factors in producing the phenotypic variability observed in the population of P. hysterophorus.
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Pre- and post-pollination barriers between two exotic and five native Sagittaria species: Implications for species conservation
Ting-Ting Zou, Sen-Tao Lyu, Qi-Lin Jiang, Shu-He Shang, Xiao-Fan Wang
Plant Diversity    2023, 45 (04): 456-468.   DOI: 10.1016/j.pld.2022.10.001
Abstract18)      PDF (3902KB)(18)       Save
Anthropogenic introduction of species has resulted in a breakdown of geographical barriers and hybridization in previously allopatric species. Thus, examining hybridization proneness of exotic species contributes to revealing its potential threat. Moreover, reproductive barriers may be strengthened or weakened due to long-term geographical isolation for these newly sympatric species. However, few studies have evaluated multiple barriers between alien and native species. In this study, we quantified the importance of four pre-pollination barriers (phenological, floral traits, pollen production, and floral constancy) and four post-pollination barriers (pollen-pistil incompatibility, seed set, seed viability, and seedling survival) between two introduced and five native Sagittaria species. Results showed that introduced S. platyphylla was cross-compatible with two native species, whereas introduced S. montevidensis was incapable of hybridizing with any native species. Different barriers were asymmetric within species pairs and multiple barriers acted in concert to maintain species boundaries. Post-pollination barriers contributed more to total reproductive isolation in native species, whereas pre-pollination barriers played a stronger role in total reproductive isolation for two introduced species. Seed set was the only barrier that was positively correlated with genetic distance. Our results provide a perspective to better understand reproductive barriers for secondary contact species. We highlight the importance of monitoring hybridization events before human introduction and the possible conservation strategies to remove invasive species with hybridization proneness.
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Historical development of karst evergreen broadleaved forests in East Asia has shaped the evolution of a hemiparasitic genus Brandisia (Orobanchaceae)
Zhe Chen, Zhuo Zhou, Ze-Min Guo, Truong Van Do, Hang Sun, Yang Niu
Plant Diversity    2023, 45 (05): 501-512.   DOI: 10.1016/j.pld.2023.03.005
Abstract17)      PDF (13024KB)(7)       Save
Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests (EBLFs), with distribution centers in the karst regions of Yunnan, Guizhou, and Guangxi in southwestern China. Based on the hemiparasitic and more or less liana habits of this genus, we hypothesized that its evolution and distribution were shaped by the development of EBLFs there. To test our hypothesis, the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci (nrDNA, PHYA and PHYB); then divergence time and ancestral areas were inferred using the combined nuclear loci dataset. Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae, with unstable placements caused by nuclear-plastid incongruences. Within Brandisia, three major clades were well supported, corresponding to the three subgenera based on morphology. Brandisia was inferred to have originated in the early Oligocene (32.69 Mya) in the Eastern Himalayas–SW China, followed by diversification in the early Miocene (19.45 Mya) in karst EBLFs. The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region (e.g., Fagaceae, Lauraceae, Theaceae, and Magnoliaceae) and the colonization of other characteristic groups (e.g., Gesneriaceae and Mahonia). These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia. In addition, the woody and parasitic habits, and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.
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Effects of land-use types and the exotic species, Hypochaeris radicata, on plant diversity in human-transformed landscapes of the biosphere reserve, Jeju Island, Korea
Deokjoo Son, Bruce Waldman, Uhram Song
Plant Diversity    2023, 45 (06): 685-693.   DOI: 10.1016/j.pld.2023.01.002
Abstract17)      PDF (3859KB)(12)       Save
Land-use and plant invasion influence biodiversity. Understanding the effects of land-use types and invasive plants on the ecosystem is crucial for better management and the development of strategic plans for increasing biodiversity in Jeju Island, Korea, a designated Biosphere Reserve by the United Nations Education, Scientific, and Cultural Organization. The effect of the most dominant invasive exotic species, Hypochaeris radicata, on the four land-use types of Jeju Island was investigated. Plant composition, soil characteristics, and plant diversity among four land-use types (cropland, green space, neglected land, and residential) were compared. Among the land-use types, croplands had the most diverse plant composition and the highest richness in exotic and native plant species. Croplands, such as tangerine orchards, which are widely distributed throughout Jeju Island, showed the highest plant diversity because of medium intensity disturbance caused by weed removal. The relative cover of H. radicata did not differ between land-use types. However, H. radicata invasion was negatively related with plant species richness, making this invasive species a threat to the biodiversity of native herbs present in land-use areas. H. radicata adapts to areas with a broad range of soil properties and a variety of land-use types. Therefore, it is crucial to monitor land-use types and patterns of plant invasion to guide the implementation of consistent management and conservation strategies for maintaining ecosystem integrity of the transformed habitat in Jeju Island.
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Corrigendum to Patterns of floristic inventory and plant collections in Myanmar [Plant Divers. 45 (3) (2023) 302-308]
Thant Sin Aung, Alice C. Hughes, Phyo Kay Khine, Bo Liu, Xiao-Li Shen, Ke-Ping Ma
Plant Diversity    2023, 45 (06): 757-758.   DOI: 10.1016/j.pld.2023.10.002
Abstract15)      PDF (738KB)(9)       Save
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Root structure syndromes of four families of monocots in the Middle Urals
Anna A. Betekhtina, Daria E. Tukova, Denis V. Veselkin
Plant Diversity    2023, 45 (06): 722-731.   DOI: 10.1016/j.pld.2023.01.007
Abstract15)      PDF (13975KB)(8)       Save
The present article tests the following general assumption: plant taxa with different specializations towards mycorrhizal interactions should have different root syndromes. Roots of 61 species common in boreal zone were studied: 16 species of Poaceae, 24 species of Cyperaceae, 14 species of Orchidaceae, and 7 species of Iridaceae. Using a fixed material of 5 individuals of each species, the following was determined: number of orders of branching roots; transverse dimensions of root, stele and cortex; number of primary xylem vessels and exodermis layers; length of root hairs; abundance of mycorrhiza. Species of each family had well-defined syndromes. Roots of Orchidaceae and Iridaceae were thick with a large stele and developed exodermis. Orchidaceae had no branching roots and had long root hairs. In Iridaceae, roots were branched, and root hairs were short. Roots of Poaceae and Cyperaceae were thin with a relatively thin stele. Root hairs were short in Poaceae and long in Cyperaceae. Our finding that root syndromes of four families of monocots differed is a new and unexpected discovery. The high specificity of root syndromes in Cyperaceae, Iridaceae, Poaceae, and Orchidaceae indicates that species of these families use different strategies to obtain water and soil nutrients.
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Evidence of the oldest extant vascular plant (horsetails) from the Indian Cenozoic
Sampa Kundu, Taposhi Hazra, Tapan Chakraborty, Subir Bera, Mahasin Ali Khan
Plant Diversity    2023, 45 (05): 569-589.   DOI: 10.1016/j.pld.2023.01.004
Abstract15)      PDF (61764KB)(8)       Save
Equisetum (Equisetaceae) has long been a focus of attention for botanists and palaeontologists because, given its extensive and well-documented fossil record, it is considered the oldest extant vascular plant and a key element in understanding vascular plant evolution. However, to date, no authentic fossil evidence of Equisetum has been found from the Indian Cenozoic. Here, we describe a new fossil species, namely, E. siwalikum sp. nov., recovered from the middle Siwalik (Late Miocene) sediments of Himachal Pradesh, western Himalaya. We identified fossil specimens based on morphological and epidermal characters. In addition, X-Ray diffraction (XRD) analysis was used to determine the mineral composition of compressed stems of Equisetum. The close affinity of our recovered Siwalik fossils to Equisetum is supported by the presence of both macromorphological and epidermal characters. Because Equisetum generally grows in wet conditions around water reservoirs, our findings indicate that the fossil locality was humid and surrounded by swamp and lowland regions during deposition. Ample fossil evidence indicates that this sphenopsid once existed in the western Himalaya during the Siwalik period. However, at present Equisetum is confined to a particular area of our fossil locality, probably a consequence of severe environmental changes coupled with competition from opportunistic angiosperms. Our discovery of Equisetum fossils in appreciable numbers from the Siwalik sediments of the Himachal Himalayas is unique and constitutes the first reliable recognition of Equisetum from the Indian Cenozoic.
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A novel seed cone of Pinus from the Miocene of coastal Southeast China indicates kinship with Southeast Asian pines
Xiang-Chuan Li, Yi Hu, Xiang Zhang, Liang Xiao, Li-Na Liang, Rui-Zhi Zhang, Lei Qiao
Plant Diversity    2023, 45 (06): 732-747.   DOI: 10.1016/j.pld.2022.12.002
Abstract14)      PDF (24748KB)(9)       Save
Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests. Pinus species richness is currently concentrated in subtropical mid-low latitudes of the Northern Hemisphere, differing from the latitudinal diversity gradient mostly recognized in woody angiosperms. How the present pattern was developing in Earth's past is still poorly studied, particularly in eastern Asia. Here, a new fossil species, Pinus shengxianica sp. nov. is described based on a fossil seed cone from the Late Miocene Shengxian Formation in Zhejiang, southeast China. A co-occurring cone is recognized as a known fossil species, Pinus speciosa Li. Extensive comparison of extant and fossil members of Pinus suggests P. shengxianica shares a striking cone similarity to Pinus merkusii and Pinus latteri (subsection Pinus) from tropical Southeast Asia in having annular bulges around the umbo on the apophysis. The morphological resemblance indicates these two extant low-latitude pines probably possess a close affinity with the present newly-discovered P. shengxianica and originated from East Asian mid-low latitude ancestors during this generic re-diversification in the Miocene. This scenario is consistent with the evolutionary trajectory reflected by the pine fossil history and molecular data, marking the Miocene as a key period for the origin and evolution of most extant pines globally. The co-occurrences of diverse conifers and broadleaved angiosperms preferring diverse niches demonstrate Late Miocene eastern Zhejiang was one of the hot spots for coniferophyte diversity and hosted a needled-broadleaved mixed forest with complex vegetation structure and an altitudinal zonation.
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Degree of style coiling is associated with corolla-tube length in the nectarless flowers of Roscoea schneideriana
Bo Wang, Ze-Yu Tong, Ying-Ze Xiong, Xiao-Fan Wang, W. Scott Armbruster, Shuang-Quan Huang
Plant Diversity    2023, 45 (06): 748-751.   DOI: 10.1016/j.pld.2022.12.004
Abstract13)      PDF (2029KB)(4)       Save
The plant-pollinator ‘arms race’ model posits that a major driver of the evolution of elongated corollas in flowers is reciprocal selection for ‘morphological fit’ between pollinator-tongue length and access distance to nectar (usually corolla-tube length). Evidence for the pollinator-mediated selection on tube length and evolution of multiple, correlated floral traits remains inconclusive. To gain possible insights into the strength of stabilizing selection by assessing standing phenotypic variation, we measured a series of functionally important floral traits, including corolla tube length and ‘effective’ tube depth and degree of style coiling. We then calculated coefficients of variation (CV) for these traits in three field populations of R. schneideriana. Unlike in most long-tubed flowers, the bottom part of the corolla tube is completely occupied by the style, with no room for nectar. The length of this portion of the corolla tube was more variable (higher CV) than the upper part of the corolla tube, suggesting that functional tube depth was under stronger stabilizing selection. The degree of style coiling was negatively related to the corolla-tube length in all three populations of R. schneideriana, suggesting that there may be conflicting selection acting on style length and corolla-tube length, which are otherwise usually tightly correlated. Given the lack of nectar in the flowers of this species, the long corolla tubes and long styles may represent morphological holdovers from ancestors that were pollinated by long-tongued pollinators, as is still seen in related species in the western Himalayas.
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Climate change impacts the distribution of Quercus section Cyclobalanopsis (Fagaceae), a keystone lineage in East Asian evergreen broadleaved forests
Lin Lin, Xiao-Long Jiang, Kai-Qi Guo, Amy Byrne, Min Deng
Plant Diversity    2023, 45 (05): 552-568.   DOI: 10.1016/j.pld.2023.03.014
Abstract13)      PDF (7217KB)(6)       Save
East Asian evergreen broadleaved forests (EBFLs) harbor high species richness, but these ecosystems are severely impacted by global climate change and deforestation. Conserving and managing EBLFs requires understanding dominant tree distribution dynamics. In this study, we used 29 species in Quercus section Cyclobalanopsis—a keystone lineage in East Asian EBLFs—as proxies to predict EBLF distribution dynamics using species distribution models (SDMs). We examined climatic niche overlap, similarity, and equivalency among seven biogeographical regions’ species using ‘ecospat’. We also estimated the effectiveness of protected areas in the predicted range to elucidate priority conservation regions. Our results showed that the climatic niches of most geographical groups differ. The western species under the Indian summer monsoon regime were mainly impacted by temperature factors, whereas precipitation impacted the eastern species under the East Asian summer monsoon regime. Our simulation predicted a northward range expansion of section Cyclobalanopsis between 2081 and 2100, except for the ranges of the three Himalayan species analyzed, which might shrink significantly. The greatest shift of highly suitable areas was predicted for the species in the South Pacific, with a centroid shift of over 300 km. Remarkably, only 7.56% of suitable habitat is currently inside protected areas, and the percentage is predicted to continue declining in the future. To better conserve Asian EBLFs, establishing nature reserves in their northern distribution ranges, and transplanting the populations with predicted decreasing numbers and degraded habitats to their future highly suitable areas, should be high-priority objectives.
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Integrating high-volume molecular and morphological data into the evolutionary studies of Allium
Xing-Jin He
Plant Diversity    2024, 46 (01): 1-2.   DOI: 10.1016/j.pld.2023.12.002
Abstract13)      PDF (362KB)(12)       Save
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Flower morphology of Allium (Amaryllidaceae) and its systematic significance
Ju Eun Jang, Shukherdorj Baasanmunkh, Nudkhuu Nyamgerel, Seung-Yoon Oh, Jun-Ho Song, Ziyoviddin Yusupov, Komijlon Tojibaev, Hyeok Jae Choi
Plant Diversity    2024, 46 (01): 3-27.   DOI: 10.1016/j.pld.2023.06.009
Abstract12)      PDF (233838KB)(12)       Save
Allium is a complicated genus that includes approximately 1000 species. Although its morphology is well studied, the taxonomic importance of many morphological traits, including floral traits, are poorly understood. Here, we examined and measured the floral characteristics of 87 accessions of 74 Allium taxa (belonging to 30 sections and nine subgenera) from Central to Eastern Asian countries. We then examined the taxonomic relationships between select flower characteristics and a phylogenetic tree based on ITS sequences. Our results confirm that floral morphology provides key taxonomic information to assess species delimitation in Allium. We found that perianth color is an important characteristic within the subg. Melanocrommyum, Polyprason, and Reticulatobulbosa. In subg. Allium, Cepa, and Rhizirideum, significant characteristics include ovary shape, perianth shape, and inner tepal apex. For species in subg. Angunium, the key taxonomic character is ovule number (only one ovule in per locule). In the subg. Allium, Cepa, Polyprason, and Reticulatobulbosa, which belong to the third evolutionary line of Allium, hood-like appendages occur in the ovary, although these do not occur in subg. Rhizirideum. Our results also indicated that the flower morphology of several species in some sections are not clearly distinguished, e.g., sect. Sacculiferum (subg. Cepa) and sect. Tenuissima (subg. Rhizirideum). This study provides detailed photographs and descriptions of floral characteristics and information on general distributions, habitats, and phenology of the studied taxa.
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Life forms affect beta-diversity patterns of larch forests in China
Wenjing Fang, Qiong Cai, Chengjun Ji, Jiangling Zhu, Zhiyao Tang, Jingyun Fang
Plant Diversity    2024, 46 (01): 49-58.   DOI: 10.1016/j.pld.2023.10.003
Abstract7)      PDF (16341KB)(8)       Save
Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch (Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components (species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total beta-diversity and its components in different life forms (i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total beta-diversity of larch forests was mainly dependent on the species turnover component. In all life forms, total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%–25% of total beta-diversity, 18%–27% of species turnover component, and 4%–16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.
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A phylogenetic approach identifies patterns of beta diversity and floristic subregions of the Qinghai-Tibet Plateau
Haibin Yu, Man Yang, Zixin Lu, Weitao Wang, Fangyuan Yu, Yonghua Zhang, Xue Yin, Hongjun Yu, Junjie Hu, David C. Deane
Plant Diversity    2024, 46 (01): 59-69.   DOI: 10.1016/j.pld.2023.07.006
Abstract5)      PDF (19817KB)(6)       Save
Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota. The Qinghai-Tibet Plateau (QTP) harbors an exceptionally diverse flora, however, a phylogenetic perspective has rarely been used to investigate its beta diversity and floristic regions. In this study, we used a phylogenetic approach to identify patterns of beta diversity and quantitatively delimit floristic regions on the Qinghai-Tibet Plateau. We also examined the relationships between multifaceted beta diversity, geographical distance, and climatic difference, and evaluated the relative importance of various factors (i.e., climate, topography and history) in shaping patterns of beta diversity. Sørensen dissimilarity indices indicated that patterns of species turnover among sites dominated the QTP. We also found that patterns of both taxonomic and phylogenetic beta diversity were significantly related to geographical distance and climatic difference. The environmental factors that contributed most to these patterns of beta diversity include annual precipitation, mean annual temperature, climatic gradients and climatic instability. Hierarchical dendrograms of dissimilarity and non-metric multidimensional scaling ordination based on phylogenetic beta diversity data identified ten floristic subregions in the QTP. Our results suggest that the contemporary environment and historical climate changes have filtered species composition among sites and eventually determined beta diversity patterns of plants in the QTP.
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Phylotranscriptomic discordance is best explained by incomplete lineage sorting within Allium subgenus Cyathophora and thus hemiplasy accounts for interspecific trait transition
Zengzhu Zhang, Gang Liu, Minjie Li
Plant Diversity    2024, 46 (01): 28-38.   DOI: 10.1016/j.pld.2023.07.004
Abstract5)      PDF (4614KB)(5)       Save
The transition of traits between genetically related lineages is a fascinating topic that provides clues to understanding the drivers of speciation and diversification. Much can be learned about this process from phylogeny-based trait evolution. However, such inference is often plagued by genome-wide gene-tree discordance (GTD), mostly due to incomplete lineage sorting (ILS) and/or introgressive hybridization, especially when the genes underlying the traits appear discordant. Here, by collecting transcriptomes, whole chloroplast genomes (cpDNA), and population genetic datasets, we used the coalescent model to turn GTD into a source of information for ILS and employed hemiplasy to explain specific cases of apparent “phylogenetic discordance” between different morphological traits and probable species phylogeny in the Allium subg. Cyathophora. Both concatenation and coalescence methods consistently showed the same phylogenetic topology for species tree inference based on single-copy genes (SCGs), as supported by the KS distribution. However, GTD was high across the genomes of subg. Cyathophora: ~27%–38.9% of the SCG trees were in conflict with the species tree. Plasmid and nuclear incongruence was also present. Our coalescent simulations indicated that such GTD was mainly a product of ILS. Our hemiplasy risk factor calculations supported that random fixation of ancient polymorphisms in different populations during successive speciation events along the subg. Cyathophora phylogeny may have caused the character transition, as well as the anomalous cpDNA tree. Our study exemplifies how phylogenetic noise can be transformed into evolutionary information for understanding character state transitions along species phylogenies.
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Community structure and species diversity dynamics of a subtropical evergreen broad-leaved forest in China: 2005 to 2020
Shi-Guang Wei, Lin Li, Kun-Dong Bai, Zhi-Feng Wen, Jing-Gang Zhou, Qin Lin
Plant Diversity    2024, 46 (01): 70-77.   DOI: 10.1016/j.pld.2023.07.005
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Here, we characterize the temporal and spatial dynamics of forest community structure and species diversity in a subtropical evergreen broad-leaved forest in China. We found that community structure in this forest changed over a 15-year period. Specifically, renewal and death of common species was large, with the renewal of individuals mainly concentrated within a few populations, especially those of Aidia canthioides and Cryptocarya concinna. The numbers of individual deaths for common species were concentrated in the small and mid-diameter level. The spatial distribution of community species diversity fluctuated in each monitoring period, showing a more dispersed diversity after the 15-year study period, and the coefficient of variation on quadrats increased. In 2010, the death and renewal of the community and the spatial variation of species diversity were different compared to other survey years. Extreme weather may have affected species regeneration and community stability in our subtropical monsoon evergreen broad-leaved forests. Our findings suggest that strengthening the monitoring and management of the forest community will help better understand the long- and short-term causes of dynamic fluctuations of community structure and species diversity, and reveal the factors that drive changes in community structure.
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Megafossils of Betulaceae from the Oligocene of Qaidam Basin and their paleoenvironmental and phytogeographic implications
Tao Yang, Jia-Hao Cai, Yan-Zhi Dai, Hong-Yu Chen, Lei Han, Li Zhang, Wei-Yu Liang, Xu-Jun Li, Wen-Jia Li, Jing-Yu Wu, San-Ping Xie, De-Fei Yan
Plant Diversity    2024, 46 (01): 101-115.   DOI: 10.1016/j.pld.2023.03.007
Abstract4)      PDF (36450KB)(23)       Save
Understanding the paleoenvironment and phytogeographical history of the Tibetan Plateau, China relies on discovering new plant fossils. The Qaidam Basin has long been regarded as an ideal ‘field laboratory’ to investigate the paleoclimate and paleobiological evolution of the northern Tibetan Plateau. However, fossil angiosperms from the Qaidam Basin are rare, and our knowledge of its paleovegetation is poor. Here, we report fossil leaves and fruits of Betulaceae found from the Oligocene Shangganchaigou Formation of northwestern Qaidam Basin (Huatugou area). Comparative morphological analysis led us to assign the fruits to the Betula subgenus Betula and the leaves to Carpinus grandis. These findings, together with other reported fossil plants from the same locality, reveal a close floristic linkage between the Qaidam Basin and Europe during the Oligocene. The northern pathway of this floristic exchange may have crossed through the Qaidam Basin during the late Paleogene. This floristic linkage may have been facilitated by the continuous narrowing of the Turgai Strait and stronger westerlies, which transported moisture and provided favorable climatic conditions. Indeed, fossil plants collected from the Qaidam Basin suggest that during the Oligocene this region had warm and humid deciduous broad-leaf forest, which differs from the region’s modern vegetation and indicates that the Qaidam Basin may have been a suitable region for these plants to flourish and spread during the Oligocene.
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Projected impacts of climate change on the habitat of Xerophyta species in Africa
Vincent Okelo Wanga, Boniface K. Ngarega, Millicent Akinyi Oulo, Elijah Mbandi Mkala, Veronicah Mutele Ngumbau, Guy Eric Onjalalaina, Wyclif Ochieng Odago, Consolata Nanjala, Clintone Onyango Ochieng, Moses Kirega Gichua, Robert Wahiti Gituru, Guang-Wan Hu
Plant Diversity    2024, 46 (01): 91-100.   DOI: 10.1016/j.pld.2023.05.001
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Climate change poses a serious long-term threat to biodiversity. To effectively reduce biodiversity loss, conservationists need to have a thorough understanding of the preferred habitats of species and the variables that affect their distribution. Therefore, predicting the impact of climate change on species-appropriate habitats may help mitigate the potential threats to biodiversity distribution. Xerophyta, a monocotyledonous genus of the family Velloziaceae is native to mainland Africa, Madagascar, and the Arabian Peninsula. The key drivers of Xerophyta habitat distribution and preference are unknown. Using 308 species occurrence data and eight environmental variables, the MaxEnt model was used to determine the potential distribution of six Xerophyta species in Africa under past, current and future climate change scenarios. The results showed that the models had a good predictive ability (Area Under the Curve and True Skill Statistics values for all SDMs were more than 0.902), indicating high accuracy in forecasting the potential geographic distribution of Xerophyta species. The main bioclimatic variables that impacted potential distributions of most Xerophyta species were mean temperature of the driest quarter (Bio9) and precipitation of the warmest quarter (Bio18). According to our models, tropical Africa has zones of moderate and high suitability for Xerophyta taxa, which is consistent with the majority of documented species localities. The habitat suitability of the existing range of the Xerophyta species varied based on the climate scenario, with most species experiencing a range loss greater than the range gain regardless of the climate scenario. The projected spatiotemporal patterns of Xerophyta species help guide recommendations for conservation efforts.
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The first mitogenome of Lauraceae (Cinnamomum chekiangense)
Changwei Bi, Ning Sun, Fuchuan Han, Kewang Xu, Yong Yang, David K. Ferguson
Plant Diversity    2024, 46 (01): 144-148.   DOI: 10.1016/j.pld.2023.11.001
Abstract3)      PDF (3708KB)(2)       Save
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How to fill the biodiversity data gap: Is it better to invest in fieldwork or curation?
Carlos A. Vargas, Marius Bottin, Tiina Sarkinen, James E. Richardson, Marcela Celis, Boris Villanueva, Adriana Sanchez
Plant Diversity    2024, 46 (01): 39-48.   DOI: 10.1016/j.pld.2023.06.003
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Data gaps and biases are two important issues that affect the quality of biodiversity information and downstream results. Understanding how best to fill existing gaps and account for biases is necessary to improve our current information most effectively. Two current main approaches for obtaining and improving data include (1) curation of biological collections, and (2) fieldwork. However, the comparative effectiveness of these approaches in improving biodiversity data remains little explored. We used the Flora de Bogotá project to study the magnitude of change in species richness, spatial coverage, and sample coverage of plant records based on curation versus fieldwork. The process of curation resulted in a decrease in species richness (synonym and error removal), but it significantly increased the number of records per species. Fieldwork contributed to a slight increase in species richness, via accumulation of new records. Additionally, curation led to increases in spatial coverage, species observed by locality, the number of plant records by species, and localities by species compared to fieldwork. Overall, curation was more efficient in producing new information compared to fieldwork, mainly because of the large number of records available in herbaria. We recommend intensive curatorial work as the first step in increasing biodiversity data quality and quantity, to identify bias and gaps at the regional scale that can then be targeted with fieldwork. The stepwise strategy would enable fieldwork to be planned more cost-effectively given the limited resources for biodiversity exploration and characterization.
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Conservation genomic investigation of an endangered conifer, Thuja sutchuenensis, reveals low genetic diversity but also low genetic load
Tongzhou Tao, Richard I. Milne, Jialiang Li, Heng Yang, Shiyang Wang, Sihan Chen, Kangshan Mao
Plant Diversity    2024, 46 (01): 78-90.   DOI: 10.1016/j.pld.2023.06.005
Abstract1)      PDF (2074KB)(9)       Save
Endangered species generally have small populations with low genetic diversity and a high genetic load. Thuja sutchuenensis is an endangered conifer endemic to southwestern China. It was once considered extinct in the wild, but in 1999 was rediscovered. However, little is known about its genetic load. We collected 67 individuals from five wild, isolated T. sutchuenensis populations, and used 636,151 SNPs to analyze the level of genetic diversity and genetic load in T. sutchuenensis to delineate the conservation units of T. sutchuenensis, based on whole transcriptome sequencing data, as well as target capture sequencing data. We found that populations of T. sutchuenensis could be divided into three groups. These groups had low levels genetic diversity and were moderately genetically differentiated. Our findings also indicate that T. sutchuenensis suffered two severe bottlenecks around the Last Glaciation Period and Last Glacial Maximum. Among Thuja species, T. sutchuenensis presented the lowest genetic load and hence might have purged deleterious mutations efficiently through purifying selection. However, distribution of fitness effects analysis indicated a high extinction risk for T. sutchuenensis. Multiple lines of evidence identified three management units for T. sutchuenensis. Although T. sutchuenensis possesses a low genetic load, low genetic diversity, suboptimal fitness, and anthropogenic pressures all present an extinction risk for this rare conifer. This might also hold true for many endangered plant species in the mountains all over the world.
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Large-scale interplant exchange of macromolecules between soybean and dodder under nutrient stresses
Jingxiong Zhang, Shalan Li, Wenxing Li, Zerui Feng, Shuhan Zhang, Xijie Zheng, Yuxing Xu, Guojing Shen, Man Zhao, Guoyan Cao, Xuna Wu, Jianqiang Wu
Plant Diversity    2024, 46 (01): 116-125.   DOI: 10.1016/j.pld.2023.11.005
Abstract1)      PDF (2295KB)(1)       Save
Parasitic plants and their hosts communicate through haustorial connections. Nutrient deficiency is a common stress for plants, yet little is known about whether and how host plants and parasites communicate during adaptation to such nutrient stresses. In this study, we used transcriptomics and proteomics to analyze how soybean (Glycine max) and its parasitizing dodder (Cuscuta australis) respond to nitrate and phosphate deficiency (-N and -P). After -N and -P treatment, the soybean and dodder plants exhibited substantial changes of transcriptome and proteome, although soybean plants showed very few transcriptional responses to -P and dodder did not show any transcriptional changes to either -N or -P. Importantly, large-scale interplant transport of mRNAs and proteins was detected. Although the mobile mRNAs only comprised at most 0.2% of the transcriptomes, the foreign mobile proteins could reach 6.8% of the total proteins, suggesting that proteins may be the major forms of interplant communications. Furthermore, the interplant mobility of macromolecules was specifically affected by the nutrient regimes and the transport of these macromolecules was very likely independently regulated. This study provides new insight into the communication between host plants and parasites under stress conditions.
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Lipid concentration and composition in xylem sap of woody angiosperms from a tropical savanna and a seasonal rainforest
Ling-Bo Huang, Xinyi Guan, Amy Ny Aina Aritsara, Jun-Jie Zhu, Steven Jansen, Kun-Fang Cao
Plant Diversity    2024, 46 (01): 126-133.   DOI: 10.1016/j.pld.2023.07.001
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Lipids may play an important role in preventing gas embolisms by coating nanobubbles in xylem sap. Few studies on xylem sap lipids have been reported for temperate plants, and it remain unclear whether sap lipids have adaptational significance in tropical plants. In this study, we quantify the lipid composition of xylem sap for angiosperm species from a tropical savanna (seven species) and a seasonal rainforest (five species) using mass spectrometry. We found that all twelve species studied contained lipids in their xylem sap, including galactolipids, phospholipids and triacylglycerol, with a total lipid concentration ranging from 0.09 to 0.26 nmol/L. There was no difference in lipid concentration or composition between plants from the two sites, and the lipid concentration was negatively related to species’ open vessel volume. Furthermore, savanna species showed little variation in lipid composition between the dry and the rainy season. These results support the hypothesis that xylem sap lipids are derived from the cytoplasm of individual conduit cells, remain trapped inside individual conduits, and undergo few changes in composition over consecutive seasons. A xylem sap lipidomic data set, which includes 12 tropical tree species from this study and 11 temperate tree species from literature, revealed no phylogenetic signals in lipid composition for these species. This study fills a knowledge gap in the lipid content of xylem sap in tropical trees and provides additional support for their common distribution in xylem sap of woody angiosperms. It appears that xylem sap lipids have no adaptive significance.
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Spatio-temporal variation of water salinity in mangroves revealed by continuous monitoring and its relationship to floristic diversity
Wei Wang, Kun Xin, Yujun Chen, Yuechao Chen, Zhongmao Jiang, Nong Sheng, Baowen Liao, Yanmei Xiong
Plant Diversity    2024, 46 (01): 134-143.   DOI: 10.1016/j.pld.2023.06.006
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Salinity is among the most critical factors limiting the growth and species distribution of coastal plants. Water salinity in estuarine ecosystems varies temporally and spatially, but the variation patterns across different time scales and salinity fluctuation have rarely been quantified. The effects of salinity on floristic diversity in mangroves are not fully understood due to the temporal and spatial heterogeneity of salinity. In this study, we monitored water salinity at an interval of 10-min over one year in three mangrove catchment areas representing the outer part, middle part, and inner part respectively of Dongzhai Bay, Hainan, China. The number of mangrove community types and dominant mangrove species of the three catchment areas were also investigated. We found that the diurnal variation and dry-season intra-month variation in water salinity were driven by tidal cycles. The seasonal variation in water salinity was mainly driven by rainfall with higher salinity occurring in the dry season and lower salinity occurring in the wet season. Spatially, water salinity was highest at the outer part, intermediate at the middle part, and lowest at the inner part of the bay. The intra-month and annual fluctuations of water salinity were highest at the middle part and lowest at the outer part of the bay. The number of mangrove community types and dominant species were lowest at the outer part, intermediate at the middle part, and highest at the inner part of the bay. These results suggest that the temporal variation of water salinity in mangroves is driven by different factors at different time scales and therefore it is necessary to measure water salinity at different time scales to get a complete picture of the saline environment that mangroves experience. Spatially, lower salinity levels benefit mangrove species richness within a bay landscape, however, further research is needed to distinguish the effects of salinity fluctuation and salinity level in affecting mangrove species richness.
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