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25 February 2022, Volume 44 Issue 01
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  • Articles
    Inter-species mRNA transfer among green peach aphids, dodder parasites, and cucumber host plants
    Juan Song, Jinge Bian, Na Xue, Yuxing Xu, Jianqiang Wu
    2022, 44(01):  1-10.  doi:10.1016/j.pld.2021.03.004
    Abstract ( 32 )   HTML ( )   PDF (8442KB) ( 50 )   Save
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    mRNAs are transported within a plant through phloem. Aphids are phloem feeders and dodders (Cuscuta spp.) are parasites which establish phloem connections with host plants. When aphids feed on dodders, whether there is trafficking of mRNAs among aphids, dodders, and host plants and if aphid feeding affects the mRNA transfer between dodders and hosts are unclear. We constructed a green peach aphid (GPA, Myzus persicae)-dodder (Cuscuta australis)-cucumber (Cucumis sativus) tritrophic system by infesting GPAs on C. australis, which parasitized cucumber hosts. We found that GPA feeding activated defense-related phytohormonal and transcriptomic responses in both C. australis and cucumbers and large numbers of mRNAs were found to be transferred between C. australis and cucumbers and between C. australis and GPAs; importantly, GPA feeding on C. australis greatly altered inter-species mobile mRNA profiles. Furthermore, three cucumber mRNAs and three GPA mRNAs could be respectively detected in GPAs and cucumbers. Moreover, our statistical analysis indicated that mRNAs with high abundances and long transcript lengths are likely to be mobile. This study reveals the existence of inter-species and even inter-kingdom mRNA movement among insects, parasitic plants, and parasite hosts, and suggests complex regulation of mRNA trafficking.
    Potential distributional shifts in North America of allelopathic invasive plant species under climate change models
    Anson Wang, Anthony E. Melton, Douglas E. Soltis, Pamela S. Soltis
    2022, 44(01):  11-19.  doi:10.1016/j.pld.2021.06.010
    Abstract ( 29 )   HTML ( )   PDF (2462KB) ( 10 )   Save
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    Predictive studies play a crucial role in the study of biological invasions of terrestrial plants under possible climate change scenarios. Invasive species are recognized for their ability to modify soil microbial communities and influence ecosystem dynamics. Here, we focused on six species of allelopathic flowering plants—Ailanthus altissima, Casuarina equisetifolia, Centaurea stoebe ssp. micranthos, Dioscorea bulbifera, Lantana camara, and Schinus terebinthifolia—that are invasive in North America and examined their potential to spread further during projected climate change. We used Species Distribution Models (SDMs) to predict future suitable areas for these species in North America under several proposed future climate models. ENMEval and Maxent were used to develop SDMs, estimate current distributions, and predict future areas of suitable climate for each species. Areas with the greatest predicted suitable climate in the future include the northeastern and the coastal northwestern regions of North America. Range size estimations demonstrate the possibility of extreme range loss for these invasives in the southeastern United States, while new areas may become suitable in the northeastern United States and southeastern Canada. These findings show an overall northward shift of suitable climate during the next few decades, given projected changes in temperature and precipitation. Our results can be utilized to analyze potential shifts in the distribution of these invasive species and may aid in the development of conservation and management plans to target and control dissemination in areas at higher risk for potential future invasion by these allelopathic species.
    Elevational patterns of functional diversity and trait of Delphinium (Ranunculaceae) in Hengduan Mountains, China
    Li-Shen Qian, Hong-Hua Shi, Xiao-Kun Ou, Hang Sun
    2022, 44(01):  20-29.  doi:10.1016/j.pld.2021.11.004
    Abstract ( 24 )   HTML ( )   PDF (8663KB) ( 17 )   Save
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    Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity. However, previous studies have mostly examined functional diversity at the community scale. Here, we examined large-scale patterns of trait occurrence and functional diversity in Delphinium along an elevational gradient from 1000 to 5700 m in the Hengduan Mountains, SW China. Elevational distribution and trait data of 102 Delphinium species were compiled to evaluate the patterns of interspecific traits, species richness, and functional diversity. We found that the distribution of species richness showed a unimodal curve that peaked between 3500 and 4000 m; functional diversity and traits showed different patterns along an elevational gradient. The functional diversity increased at a lower rate along an elevation gradient, whereas species richness continued to increase. Species with large ranges and non-endemic species were most affected by geometric constraints. Richness of species endemic to the Hengduan Mountains peaked at higher elevations, likely due to increased speciation and restricted dispersion under alpine conditions. We conclude that the middle elevation region is not only the functionally richest but also the most functionally stable region for Delphinium, which could be insurance against environmental change. Extreme conditions and strong environmental filters in an alpine environment may cause the convergence of species traits, which could relate to reducing nutrient trait investment and increasing reproductive trait investment. We conclude that large-scale studies are consistent with previous studies at the community scale. This may indicate that the relationship between functional diversity and species richness across different scales is the same.
    Current patterns of plant diversity and phylogenetic structure on the Kunlun Mountains
    Wei-Bo Du, Peng Jia, Guo-Zhen Du
    2022, 44(01):  30-38.  doi:10.1016/j.pld.2021.04.007
    Abstract ( 33 )   HTML ( )   PDF (7081KB) ( 43 )   Save
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    Large-scale patterns of biodiversity and the underlying mechanisms that regulate these patterns are central topics in biogeography and macroecology. The Qinghai-Tibet Plateau serves as a natural laboratory for studying these issues. However, most previous studies have focused on the entire Qinghai-Tibet Plateau, leaving independent physical geographic subunits in the region less well understood. We studied the current plant diversity of the Kunlun Mountains, an independent physical geographic subunit located in northwestern China on the northern edge of the Qinghai-Tibet Plateau. We integrated measures of species distribution, geological history, and phylogeography, and analyzed the taxonomic richness, phylogenetic diversity, and community phylogenetic structure of the current plant diversity in the area. The distribution patterns of 1911 seed plants showed that species were distributed mainly in the eastern regions of the Kunlun Mountains. The taxonomic richness, phylogenetic diversity, and genera richness showed that the eastern regions of the Kunlun Mountains should be the priority area of biodiversity conservation, particularly the southeastern regions. The proportion of Chinese endemic species inhabiting the Kunlun Mountains and their floristic similarity may indicate that the current patterns of species diversity were favored via species colonization. The Hengduan Mountains, a biodiversity hotspot, is likely the largest source of species colonization of the Kunlun Mountains after the Quaternary. The net relatedness index indicated that 20 of the 28 communities examined were phylogenetically dispersed, while the remaining communities were phylogenetically clustered. The nearest taxon index indicated that 27 of the 28 communities were phylogenetically clustered. These results suggest that species colonization and habitat filtering may have contributed to the current plant diversity of the Kunlun Mountains via ecological and evolutionary processes, and habitat filtering may play an important role in this ecological process.
    Plant diversity of Hyrcanian relict forests: An annotated checklist, chorology and threat categories of endemic and near endemic vascular plant species
    Atefeh Ghorbanalizadeh, Hossein Akhani
    2022, 44(01):  39-69.  doi:10.1016/j.pld.2021.07.005
    Abstract ( 31 )   HTML ( )   PDF (51016KB) ( 16 )   Save
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    In this paper a critical annotated checklist of 256 endemic and near endemic species belonging to 152 genera and 50 families of flowering plants known from Hyrcanian relict forests is presented. Distribution maps of taxa, elevational range, number of known records, chorotypes, life forms, IUCN threat categories and habitat types are also provided. The chorotypes are categorized into eight main patterns:1) the Omni-Hyrcanian pattern (OH), 2) West Hyrcanian pattern (WH), 3) Manjil-Rudbar pattern (MR), 4) Central Hyrcanian pattern (CH), 5) Central and East Hyrcanian pattern (CEH), 6) East Hyrcanian pattern (EH), 7) Alborz-Hyrcanian pattern (AH), and 8) Euxino-Hyrcanian pattern (XH). The richness and distribution maps were generated based on 5408 records gained from herbarium specimens and literature records. The life form spectra show that the majority of taxa (54.7%) belong to hemicryptophytes, followed by the tuberous, bulbous and parasitic geophytes with 45 species (17.6%) and phanerophytes with 28 taxa (10.9%). The conservation status of species according to IUCN criteria indicates that 30 taxa are Critically Endangered, 52 taxa Endangered, 30 taxa Vulnerable, 25 taxa Near Threatened and 81 taxa are of Least Concern. Our present data were not sufficient to evaluate 38 taxa that are categorized here as Data Deficient. The new combination of Leutea translucens (=Peucedanum translucens) is validated with inclusion of Peucedanum hyrcanicum as its synonym. The disjunct occurrence of the Caucasian species Gentiana grossheimii is reported from the eastern parts of the Hyrcanian forests in Iran for the first time. We conclude that (i) the Hyrcanian forests and associated habitats in the northern slopes of the Alborz Mountains harbour tremendous floristic diversity of high conservation priority, and (ii) the Hyrcanian forest zone is an important and unique center of endemism within the Euro-Siberian region that should be considered a floristic province with a large number of relict species.
    Comparative chloroplast genome analysis of medicinally important Veratrum (Melanthiaceae) in China: Insights into genomic characterization and phylogenetic relationships
    Ying-Min Zhang, Li-Jun Han, Cong-Wei Yang, Zi-Li Yin, Xing Tian, Zi-Gang Qian, Guo-Dong Li
    2022, 44(01):  70-82.  doi:10.1016/j.pld.2021.05.004
    Abstract ( 18 )   HTML ( )   PDF (17943KB) ( 13 )   Save
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    Members of Veratrum are perennial herbs widely used in traditional Chinese medicine to induce vomiting, resolve blood stasis and relieve pain. However, the intrageneric classification and phylogenetic relationships within Veratrum have long been controversial due to the complexity of morphological variations and lack of high-resolution molecular markers. In this study, we reevaluated the infrageneric relationships with the genus Veratrum using complete chloroplast genome sequence data. Herein, the complete cp genomes of ten species of Veratrum were newly sequenced and characterized. The complete cp genomes of ten species of Veratrum had the typical quadripartite structure, ranging from 151,597 bp to 153,711 bp in size and comprising a total of 135 genes. The structure of Veratrum cp genomes (i.e., gene order, content, and genome components) was highly similar across species. The number of simple sequence repeats (SSRs) ranged from 63 to 78, and of long repeats ranged from 31 to 35. Eight highly divergent regions (ndhF, psbC-psbZ, psbK-psbI, rpoB-trnC_GCA, trnK_UUU-trnQ_UUG, trnS_GCU-trnG_UCC, trnT_UGU-trnL_UAA and ycf1) were identified and are potentially useful for the DNA barcoding of Veratrum. Phylogenetic analysis among 29 taxa based on cp genomes, total genes, protein-coding genes and intergenic regions strongly supported the monophyly of Veratrum. The circumscription and relationships of the infrageneric taxa of Veratrum were well-presented with great resolution. These results will facilitate the identification, taxonomy, and utilization of Veratrum plants as well as the evolutionary studies of Melanthiaceae.
    Mojiangia oreophila (Crepidinae, Cichorieae, Asteraceae), a new species and genus from Mojiang County, SW Yunnan, China, and putative successor of the maternal Faberia ancestor
    Zhi-Jian Yin, Ze-Huan Wang, Norbert Kilian, Ying Liu, Hua Peng, Ming-Xu Zhao
    2022, 44(01):  83-93.  doi:10.1016/j.pld.2021.06.007
    Abstract ( 19 )   HTML ( )   PDF (54212KB) ( 14 )   Save
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    A single small population of chasmophytic plants is described as Mojiangia oreophila, a monotypic genus in the subtribe Crepidinae, characterised by a unique combination of morphological features, in particular densely long-papillose homomorphic achenes with five main ribs each accompanied by two secondary ribs, coarse brownish pappus bristles, moderately many-flowered capitula, a small involucre with numerous outer phyllaries, perennial rosette herb growth and brown-woolly caudex and leaf axils. Molecular phylogenetic analysis detected that in the nrITS phylogeny M. oreophila forms a clade of its own in the Crepidinae; in the plastid DNA phylogeny it is nested in the clade formed by the hybridogenous genus Faberia, the maternal ancestor of which comes from the Crepidinae and the paternal ancestor from the Lactucinae, where Faberia is placed in nrITS phylogenies. M. oreophila shares several morphological features with Faberia and also shares the expected chromosome number of 2n=16 with its hitherto unknown maternal ancestor. M. oreophila may therefore be a successor of the maternal ancestor of Faberia. Alternatively, cytonuclear discordance is to be assumed in Mojiangia, caused by chloroplast capture as a result of hybridisation and introgression with Faberia.
    Seed dormancy, germination and storage behavior of Magnolia sinica, a plant species with extremely small populations of Magnoliaceae
    Liang Lin, Lei Cai, Lei Fan, Jun-Chao Ma, Xiang-Yun Yang, Xiao-Jian Hu
    2022, 44(01):  94-100.  doi:10.1016/j.pld.2021.06.009
    Abstract ( 11 )   HTML ( )   PDF (9216KB) ( 12 )   Save
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    Magnolia sinica is one of the most endangered Magnoliaceae species in China. Seed biology information concerning its long-term ex situ conservation and utilization is insufficient. This study investigated dormancy status, germination requirements and storage behavior of M. sinica. Freshly matured seeds germinated to ca. 86.5% at 25/15℃ but poorly at 30℃; GA3 and moist chilling promoted germination significantly at 20℃. Embryos grew at temperatures (alternating or constant) between 20℃ and 25℃, but not at 5℃ or 30℃. Our results indicate that M. sinica seeds possibly have non-deep simple morphophysiological dormancy (MPD). Seeds survived desiccation to 9.27% and 4.85% moisture content (MC) as well as a further 6-month storage at -20℃ and in liquid nitrogen, including recovery in vitro as excised embryos. The established protocol ensured that at least 58% of seedlings were obtained after both cold storage and cryopreservation. These results indicate that both conventional seed banking and cryopreservation have potential as long-term ex situ conservation methods, although further optimized approaches are recommended for this critically endangered magnolia species.
    Leaf physiological and anatomical responses of two sympatric Paphiopedilum species to temperature
    Jing-Qiu Feng, Ji-Hua Wang, Shi-Bao Zhang
    2022, 44(01):  101-108.  doi:10.1016/j.pld.2021.05.001
    Abstract ( 16 )   HTML ( )   PDF (2730KB) ( 12 )   Save
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    Paphiopedilum dianthum and P. micranthum are two endangered orchid species, with high ornamental and conservation values. They are sympatric species, but their leaf anatomical traits and flowering period have significant differences. However, it is unclear whether the differences in leaf structure of the two species will affect their adaptabilities to temperature. Here, we investigated the leaf photosynthetic, anatomical, and flowering traits of these two species at three sites with different temperatures (Kunming, 16.7 ± 0.2℃; Puer, 17.7 ± 0.2℃; Menglun, 23.3 ± 0.2℃) in southwest China. Compared with those at Puer and Kunming, the values of light-saturated photosynthetic rate (Pmax), stomatal conductance (gs), leaf thickness (LT), and stomatal density (SD) in both species were lower at Menglun. The values of Pmax, gs, LT, adaxial cuticle thickness (CTad) and SD in P. dianthum were higher than those of P. micranthum at the three sites. Compared with P. dianthum, there were no flowering plants of P. micranthum at Menglun. These results indicated that both species were less resistance to high temperature, and P. dianthum had a stronger adaptability to high-temperature than P. micranthum. Our findings can provide valuable information for the conservation and cultivation of Paphiopedilum species.
    Phytochrome B regulates jasmonic acid-mediated defense response against Botrytis cinerea in Arabidopsis
    Shengyuan Xiang, Songguo Wu, Yifen Jing, Ligang Chen, Diqiu Yu
    2022, 44(01):  109-115.  doi:10.1016/j.pld.2021.01.007
    Abstract ( 20 )   HTML ( )   PDF (3010KB) ( 5 )   Save
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    The phytochrome B mediated light signaling integrates with various phytohormone signalings to control plant immune response. However, it is still unclear whether phyB-mediated light signaling has an effect on the biosynthesis of jasmonate during plant defense response against Botrytis cinerea. In this study, we demonstrated that phyB-mediated light signaling has a role in this process. Initially, we confirmed that phyb plants were obviously less resistant to B. cinerea while phyB overexpressing plants showed significantly enhanced resistance. We also found that the expression of numerous JA biosynthesis genes was promoted upon treatment with red or white light when compared to that of darkness, and that this promotion is dependent on phyB. Consistent with the gene expression results, phyb plants accumulated reduced pool of JA-Ile, indicating that phyB-mediated light signaling indeed increased JA biosynthesis. Further genetic analysis showed that light-mediated JAZ9 degradation and phyB-enhanced resistance were dependent on the receptor COI1, and that pif1/3/4/5 (pifq) can largely rescue the severe symptom of phyb. Taken together, our study demonstrates that phyB may participate in plant defense against B. cinerea through the modulation of the biosynthesis of JA.
    Temporal regulation of alternative splicing events in rice memory under drought stress
    Hong Yang, Ping Li, Guihua Jin, Daping Gui, Li Liu, Chengjun Zhang
    2022, 44(01):  116-125.  doi:10.1016/j.pld.2020.11.004
    Abstract ( 17 )   HTML ( )   PDF (5870KB) ( 1 )   Save
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    Plant adaptation to drought stress is essential for plant survival and crop yield. Recently, harnessing drought memory, which is induced by repeated stress and recovery cycles, was suggested as a means to improve drought resistance at the transcriptional level. However, the genetic mechanism underlying drought memory is unclear. Here, we carried out a quantitative analysis of alternative splicing (AS) events in rice memory under drought stress, generating 12 transcriptome datasets. Notably, we identified exon skipping (ES) as the predominant AS type (>80%) in differential alternative splicing (DAS) in response to drought stress. Applying our analysis pipeline to investigate DAS events following drought stress in six other plant species revealed variable ES frequencies ranging from 9.94% to 60.70% depending on the species, suggesting that the relative frequency of DAS types in plants is likely to be species-specific. The dinucleotide sequence at AS splice sites in rice following drought stress was preferentially GC-AG and AT-AC. Since U12-type splicing uses the AT-AC site, this suggests that drought stress may increase U12-type splicing, and thus increase ES frequency. We hypothesize that multiple isoforms derived from exon skipping may be induced by drought stress in rice. We also identified 20 transcription factors and three highly connected hub genes with potential roles in drought memory that may be good targets for plant breeding.