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25 April 2022, Volume 44 Issue 02
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  • Review
    Non-host plants: Are they mycorrhizal networks players?
    Yanliang Wang, Xinhua He, Fuqiang Yu
    2022, 44(02):  127-134.  doi:10.1016/j.pld.2021.06.005
    Abstract ( 90 )   HTML ( )   PDF (1728KB) ( 60 )   Save
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    Common mycorrhizal networks (CMNs) that connect individual plants of the same or different species together play important roles in nutrient and signal transportation, and plant community organization. However, about 10% of land plants are non-mycorrhizal species with roots that do not form any well-recognized types of mycorrhizas; and each mycorrhizal fungus can only colonize a limited number of plant species, resulting in numerous non-host plants that could not establish typical mycorrhizal symbiosis with a specific mycorrhizal fungus. If and how non-mycorrhizal or non-host plants are able to involve in CMNs remains unclear. Here we summarize studies focusing on mycorrhizal-mediated host and non-host plant interaction. Evidence has showed that some host-supported both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) hyphae can access to non-host plant roots without forming typical mycorrhizal structures, while such non-typical mycorrhizal colonization often inhibits the growth but enhances the induced system resistance of non-host plants. Meanwhile, the host growth is also differentially affected, depending on plant and fungi species. Molecular analyses suggested that the AMF colonization to non-hosts is different from pathogenic and endophytic fungi colonization, and the hyphae in non-host roots may be alive and have some unknown functions. Thus we propose that non-host plants are also important CMNs players. Using non-mycorrhizal model species Arabidopsis, tripartite culture system and new technologies such as nanoscale secondary ion mass spectrometry and multi-omics, to study nutrient and signal transportation between host and non-host plants via CMNs may provide new insights into the mechanisms underlying benefits of intercropping and agro-forestry systems, as well as plant community establishment and stability.
    Global patterns of fern species diversity: An evaluation of fern data in GBIF
    Hong Qian, Jian Zhang, Mei-Chen Jiang
    2022, 44(02):  135-140.  doi:10.1016/j.pld.2021.10.001
    Abstract ( 96 )   HTML ( )   PDF (3938KB) ( 70 )   Save
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    Despite that several studies have shown that data derived from species lists generated from distribution occurrence records in the Global Biodiversity Information Facility (GBIF) are not appropriate for those ecological and biogeographic studies that require high sampling completeness, because species lists derived from GBIF are generally very incomplete, Suissa et al. (2021) generated fern species lists based on data with GBIF for 100 km × 100 km grid cells across the world, and used the data to determine fern diversity hotspots and species richness–climate relationships. We conduct an evaluation on the completeness of fern species lists derived from GBIF at the grid–cell scale and at a larger spatial scale, and determine whether fern data derived from GBIF are appropriate for studies on the relations of species composition and richness with climatic variables. We show that species sampling completeness of GBIF is low (<40%) for most of the grid cells examined, and such low sampling completeness can substantially bias the investigation of geographic and ecological patterns of species diversity and the identification of diversity hotspots. We conclude that fern species lists derived from GBIF are generally very incomplete across a wide range of spatial scales, and are not appropriate for studies that require data derived from species lists in high completeness. We present a map showing global patterns of fern species diversity based on complete or nearly complete regional fern species lists.
    Genome size evolution of the extant lycophytes and ferns
    Fa-Guo Wang, Ai-Hua Wang, Cheng-Ke Bai, Dong-Mei Jin, Li-Yun Nie, AJ Harris, Le Che, Juan-Juan Wang, Shi-Yu Li, Lei Xu, Hui Shen, Yu-Feng Gu, Hui Shang, Lei Duan, Xian-Chun Zhang, Hong-Feng Chen, Yue-Hong Yan
    2022, 44(02):  141-152.  doi:10.1016/j.pld.2021.11.007
    Abstract ( 95 )   HTML ( )   PDF (7442KB) ( 209 )   Save
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    Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.
    Evidence for two types of Aquilegia ecalcarata and its implications for adaptation to new environments
    Lei Huang, Fang-Dong Geng, Jing-Jing Fan, Wei Zhai, Cheng Xue, Xiao-Hui Zhang, Yi Ren, Ju-Qing Kang
    2022, 44(02):  153-162.  doi:10.1016/j.pld.2021.06.006
    Abstract ( 78 )   HTML ( )   PDF (13190KB) ( 29 )   Save
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    Spurs have played an important role in the radiation of the genus Aquilegia, but little is known about how the spurless state arose in A. ecalcarata. Here we aim to characterize the genetic divergence within A. ecalcarata and gain insights into the origin of this species. A total of 19 populations from A. ecalcarata and 23 populations from three of its closest relatives (Aquilegia kansuensis, Aquilegia rockii and Aquilegia yabeana) were sampled in this study. We sequenced fifteen nuclear gene fragments across the genome and three chloroplast loci to conduct phylogenetic, PCoA and STRUCTURE analyses.
    Our analyses indicate that A. ecalcarata may not be monophyletic and can be divided into two distinct lineages (A. ecalcarata I and A. ecalcarata II). A. ecalcarata I is genetically close to A. kansuensis, whereas A. ecalcarata II is close to A. rockii. Isolation-with-migration analysis suggested that historical gene flow was low between A. ecalcarata I and A. rockii, as well as between A. ecalcarata II and A. kansuensis. The two distinct lineages of A. ecalcarata show significant divergence in 13 floral traits and also have distinct distributions. In addition, both A. ecalcarata I and II are adapted to a stony environment that differs from that of their closest relatives, indicating a habitat shift may have driven new adaptations. Our findings enrich the understanding of how floral evolution contributes to species diversification.
    Intraspecific trait variation of woody species reduced in a savanna community, southwest China
    Lubing Liu, Jie Yang, Min Cao, Qinghai Song
    2022, 44(02):  163-169.  doi:10.1016/j.pld.2021.06.002
    Abstract ( 76 )   HTML ( )   PDF (3353KB) ( 41 )   Save
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    Plants deploy various ecological strategies in response to environmental heterogeneity. In many forest ecosystems, plants have been reported to have notable inter- and intra-specific trait variation, as well as clear phylogenetic signals, indicating that these species possess a degree of phenotypic plasticity to cope with habitat variation in the community. Savanna communities, however, grow in an open canopy structure and exhibit little species diversification, likely as a result of strong environmental stress. In this study, we hypothesized that the phylogenetic signals of savanna species would be weak, the intraspecific trait variation (ITV) would be low, and the contribution of intraspecific variation to total trait variance would be reduced, owing to low species richness, multiple stresses and relatively homogenous community structure. To test these hypotheses, we sampled dominant woody species in a dry-hot savanna in southwestern China, focusing on leaf traits related to adaptability of plants to harsh conditions (year-round intense radiation, low soil fertility and seasonal droughts). We found weak phylogenetic signals in leaf traits and low ITV (at both individual and canopy-layer levels). Intraspecific variation (including leaf-, layer- and individual-scales) contributed little to the total trait variance, whereas interspecific variation and variation in leaf phenology explained substantial variance. Our study suggests that intraspecific trait variation is reduced in savanna community. Furthermore, our findings indicate that classifying species by leaf phenology may help better understand how species coexist under similar habitats with strong stresses.
    Phylogenetic relationship, biogeography, and conservation genetics of endangered Fraxinus chiisanensis (Oleaceae), endemic to South Korea
    Changkyun Kim, Dong-Kap Kim, Hang Sun, Joo-Hwan Kim
    2022, 44(02):  170-180.  doi:10.1016/j.pld.2021.06.004
    Abstract ( 83 )   HTML ( )   PDF (2763KB) ( 25 )   Save
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    Endemic plants are important for understanding phylogenetic relationships, biogeographical history, and genetic variation because of their restricted distribution and their role in conserving biodiversity. Here, we investigated the phylogenetic relationships of the Korean endemic Fraxinus chiisanensis by reconstructing the molecular phylogeny of Fraxinus based on two nuclear DNA (nrITS and phantastica) and two chloroplast DNA (psbA-trnH and rpl32-trnL) regions. Within our fossil-calibrated phylogenetic framework, we also inferred the biogeographical history of F. chiisanensis. To provide a scientific basis for the conservation of F. chiisanensis, we determined the levels of genetic diversity and genetic differentiation in this species. Combining information from nuclear and chloroplast DNA sequence data, our molecular phylogenetic analyses identified F. chiisanensis as a genetically distinct unit from its sister group, Fraxinus platypoda from Japan. Our molecular dating analyses using nuclear and chloroplast DNA data sets show F. chiisanensis diverged from its sister F. platypoda in the Early or Middle Miocene and differentiated in the Late Miocene on the Korean Peninsula. Our results suggest that the divergence of F. chiisanensis was associated with the submergence of the East China Sea land bridge and enhanced monsoons in East Asia. When compared to F. platypoda, F. chiisanensis exhibits low genetic diversity within populations and high genetic differentiation among populations. These results help us to understand the evolutionary history of F. chiisanensis and to develop a conservation strategy for this species.
    A revision of Dryopteris sect. Diclisodon (Dryopteridaceae) based on morphological and molecular evidence with description of a new species
    Zheng-Yu Zuo, Ting Zhao, Xin-Yu Du, Yun Xiong, Jin-Mei Lu, De-Zhu Li
    2022, 44(02):  181-190.  doi:10.1016/j.pld.2021.09.005
    Abstract ( 164 )   HTML ( )   PDF (32144KB) ( 56 )   Save
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    Dryopteris sect. Diclisodon is a small section of ferns with about 12 species mainly distributed in East Asia. Here, we carried out morphological and phylogenetic analyses of this section. A new species from southwest China, D. gaoligongensis, is described and illustrated. Dryopteris gaoligongensis resembles D. indonesiana and D. sparsa, but differs by having a creeping rhizome and large 4-pinnate fronds. We also show that D. glabrior Ching & Z.Y. Liu is a distinct species; however, because it is a later homonym of D. glabrior Copel., it should be renamed D. renchangiana. We conclude that a species previously known as D. nitidula, also an illegitimate homonym, should be recognized with a new name, D. sinonepalensis. We resolve the phylogenetic position of D. yoroii as sister to other sampled species of D. sect. Diclisodon. Our phylogenetic analyses confirm the distinctiveness of D. gaoligongensis, D. renchangiana, and D. sinonepalensis. A key to species of D. sect. Diclisodon in China is provided.
    Diversity and species-specificity of brood pollination of leafflower trees (Phyllanthaceae: Glochidion) by leafflower moths (Lepidoptera: Epicephala) in tropical Southeast Asia (Cambodia)
    Pisal Chheang, David H. Hembry, Gang Yao, Shi-Xiao Luo
    2022, 44(02):  191-200.  doi:10.1016/j.pld.2021.07.001
    Abstract ( 79 )   HTML ( )   PDF (6860KB) ( 31 )   Save
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    Glochidion (Phyllanthaceae; leafflower trees) is a genus of trees which is widely reported to be pollinated by leafflower moths (Gracillariidae: Epicephala) in temperate and subtropical Asia, Australia, and the Pacific islands. However, the pollination ecology of Glochidion is not well described from tropical Asia, the region where it is most species-rich at both local (≤9 spp.) and regional (~200 spp.) scales. Here we report investigations of pollination biology and species-specificity of five Glochidion species in tropical Southeast Asia (Cambodia). Through nocturnal observations and fruit dissections, we find that at least three and likely five Glochidion species in Cambodia are pollinated by seed-parasitic leafflower moths. We find no evidence that any of these leafflower moths are non-mutualistic parasites, despite known examples of such parasites of this mutualism elsewhere in Asia. While the presence of a single larva in a fruit results in only a fraction of seeds being consumed, the presence of more than one larva per fruit—a frequent occurrence in some species—can result in almost all seeds within the fruit being infested. Multilocus phylogenetic analysis indicates that there are five different minimally monophyletic leafflower moth clades, each of which pollinates a unique Glochidion host species. Our results indicate that in its center of diversity in tropical Asia this system is an obligate pollination mutualism as previously described at the global margins of its distribution. These findings provide insights into the processes that generate and maintain biodiversity and maintain mutualism stability in plant–insect interactions in this biodiversity hotspot.
    Genome-wide analysis of the B3 transcription factors reveals that RcABI3/VP1 subfamily plays important roles in seed development and oil storage in castor bean (Ricinus communis)
    Wen-Bo Wang, Tao Ao, Yan-Yu Zhang, Di Wu, Wei Xu, Bing Han, Ai-Zhong Liu
    2022, 44(02):  201-212.  doi:10.1016/j.pld.2021.06.008
    Abstract ( 169 )   HTML ( )   PDF (15825KB) ( 36 )   Save
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    The B3 transcription factors (TFs) in plants play vital roles in numerous biological processes. Although B3 genes have been broadly identified in many plants, little is known about their potential functions in mediating seed development and material accumulation. Castor bean (Ricinus communis) is a non-edible oilseed crop considered an ideal model system for seed biology research. Here, we identified a total of 61 B3 genes in the castor bean genome, which can be classified into five subfamilies, including ABI3/VP1, HSI, ARF, RAV and REM. The expression profiles revealed that RcABI3/VP1 subfamily genes are significantly up-regulated in the middle and later stages of seed development, indicating that these genes may be associated with the accumulation of storage oils. Furthermore, through yeast one-hybrid and tobacco transient expression assays, we detected that ABI3/VP1 subfamily member RcLEC2 directly regulates the transcription of RcOleosin2, which encodes an oil-body structural protein. This finding suggests that RcLEC2, as a seed-specific TF, may be involved in the regulation of storage materials accumulation. This study provides novel insights into the potential roles and molecular basis of B3 family proteins in seed development and material accumulation.
    Identification and fine mapping of rtms1-D, a gene responsible for reverse thermosensitive genic male sterility from Diannong S-1X
    Xiao Zhang, Guimei Chang, Zihao Wu, Jinpeng Wan, Jun Yang, Feijun Wang, Fang Wang, Diqiu Yu, Peng Xu
    2022, 44(02):  213-221.  doi:10.1016/j.pld.2021.05.002
    Abstract ( 62 )   HTML ( )   PDF (19436KB) ( 20 )   Save
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    Thermosensitive genic male sterility (TGMS) has been widely used in two-line hybrid rice breeding. Due to hybrid seed production being highly affected by changeable environments, its application scope is limited to some extent. Thus, it is of great importance to identify potential TGMS genes in specific rice varieties. Here, Diannong S-1 xuan (DNS-1X), a reverse TGMS (RTGMS) japonica male sterile line, was identified from Diannong S-1. Genetic analysis showed that male sterility was tightly controlled by a single recessive gene, which was supported by the phenotype of the F1 and F2:3 populations derived from the cross between DNS-1X and Yunjing 26 (YJ26). Combining simple sequence repeat (SSR) markers and bulked segregation analysis (BSA), we identified a 215 kb region on chromosome 10 as a candidate reverse TGMS region, which was designated as rtms1-D. It was narrower than the previously reported RTGMS genes rtms1 and tms6(t). The fertility conversion detected in the natural environment showed that DNS-1X was sterile below 28–30 ℃; otherwise, it was fertile. Histological analysis further indicated that the pollen abortion was occurred in the young microspore stage. This study will provide new resources for two-line hybrid rice and pave the way for molecular breeding of RTGMS lines.
    Short communication
    Oreocharis xieyongii, an unusual new species of Gesneriaceae from western Hunan, China
    Zhen-Yu Lv, Ziyoviddin Yusupov, Dai-Gui Zhang, Ya-Zhou Zhang, Xiao-Shuang Zhang, Nan Lin, Komiljon Tojibaev, Hang Sun, Tao Deng
    2022, 44(02):  222-230.  doi:10.1016/j.pld.2021.11.008
    Abstract ( 118 )   HTML ( )   PDF (8603KB) ( 125 )   Save
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    A new species, Oreocharis xieyongii T. Deng, D.G. Zhang & H. Sun, from Hunan Province, central China, is described. The combination of purple zygomorphic corolla with longer adaxial lobes and exserted stamens defines the species and discriminates it from all other current Oreocharis species. Morphological traits of the new species were compared to those of two similar species, Oreocharis xiangguiensis and O. rubrostriata. Phylogenetic analysis indicates that the new species is nested within the Oreocharis. Although only half of Oreocharis species were included in our study, evolutionary character analysis indicates that the ancestral states of the genus are likely the purple corolla, longer abaxial lip and inserted stamens. The longer adaxial lip is perhaps an apomorphy and only present in O. xieyongii and O. rubrostriata. Both morphological and molecular evidence suggest that O. xieyongii is a taxon new to science.