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Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations. In this study, we used double digest restriction-site-associated DNA sequencing (ddRAD) technology to assess the genetic diversity, genetic structure and demographic history of the three extant populations of R. meddianum. Analysis of SNPs indicated that R. meddianum populations have a high genetic diversity (π = 0.0772 ± 0.0024, HE = 0.0742 ± 0.002). Both FST values (0.1582–0.2388) and AMOVA showed a moderate genetic differentiation among the R. meddianum populations. Meanwhile, STRUCTURE, PCoA and NJ trees indicated that the R. meddianum samples were clustered into three distinct genetic groups. Using the stairway plot, we found that R. meddianum underwent a population bottleneck about 70,000 years ago. Furthermore, demographic models of R. meddianum and its relative, Rhododendron cyanocarpum, revealed that these species diverged about 3.05 (2.21–5.03) million years ago. This divergence may have been caused by environmental changes that occurred after the late Pliocene, e.g., the Asian winter monsoon intensified, leading to a drier climate. Based on these findings, we recommend that R. meddianum be conserved through in situ, ex situ approaches and that its seeds be collected for germplasm.

Rhododendrons are woody plants, famous throughout the world as having high horticultural value. However, many wild species are currently threatened with extinction. Here, we report for the first time a high-quality, chromosome-level genome of Rhododendron griersonianum, which has contributed to approximately 10% of all horticultural rhododendron varieties but which in its wild form has been evaluated as critically endangered. The final genome assembly, which has a contig N50 size of approximately 34 M and a total length of 677 M, is the highest-quality genome sequenced within the genus to date, in part due to its low heterozygosity (0.18%). Identified repeats constitute approximately 57% of the genome, and 38 280 protein-coding genes were predicted with high support. We further resequenced 31 individuals of R. griersonianum as well as 30 individuals of its widespread relative R. delavayi, and performed additional conservation genomic analysis. The results showed that R. griersonianum had lower genetic diversity (θ = 2.58e-3; π = 1.94e-3) when compared not only to R. delavayi (θ = 11.61e-3, π = 12.97e-3), but also to most other woody plants. Furthermore, three severe genetic bottlenecks were detected using both the Stairway plot and fastsimcoal2 analysis, which are thought to have occurred in the late Middle Pleistocene and the Last Glacial Maximum (LGM) period. After these bottlenecks, R. griersonianum recovered and maintained a constant effective population size (>25 000) until now. Intriguingly, R. griersonianum has accumulated significantly more deleterious mutations in the homozygous state than R. delavayi, and several deleterious mutations (e.g., in genes involved in the response to heat stress) are likely to have harmed the adaptation of this plant to its surroundings. This high-quality, chromosome-level genome and the population genomic analysis of the critically endangered R. griersonianum will provide an invaluable resource as well as insights for future study in this species to facilitate conservation and in the genus Rhododendron in general.

Recent advancements in whole genome sequencing techniques capable of covering nearly all the nucleotide variations of a genome would make it possible to set up a conservation framework for threatened plants at the genomic level. Here we applied a whole genome resequencing approach to obtain genome-wide data from 105 individuals sampled from the 10 currently known extant populations of Acer yangbiense, an endangered species with fragmented habitats and restricted distribution in Yunnan, China. To inform meaningful conservation action, we investigated what factors might have contributed to the formation of its extremely small population sizes and what threats it currently suffers at a genomic level. Our results revealed that A. yangbiense has low genetic diversity and comprises different numbers of genetic groups based on neutral (seven) and selected loci (13), with frequent gene flow between populations. Repeated bottleneck events, particularly the most recent one occurring within ~10,000 years before present, which decreased its effective population size (Ne )

This paper presents a re-evaluation of the taxonomic identity of Phlomoides pararotata. Based on a comparative study of morphology and type material as well as field investigations, P. pararotata is synonymized with P. burmanica. Leaf features as well as bract morphology of this species are described.

Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations. In this study, we used double digest restriction-site-associated DNA sequencing (ddRAD) technology to assess the genetic diversity, genetic structure and demographic history of the three extant populations of R. meddianum. Analysis of SNPs indicated that R. meddianum populations have a high genetic diversity (π = 0.0772 ± 0.0024, HE = 0.0742 ± 0.002). Both FST values (0.1582–0.2388) and AMOVA showed a moderate genetic differentiation among the R. meddianum populations. Meanwhile, STRUCTURE, PCoA and NJ trees indicated that the R. meddianum samples were clustered into three distinct genetic groups. Using the stairway plot, we found that R. meddianum underwent a population bottleneck about 70,000 years ago. Furthermore, demographic models of R. meddianum and its relative, Rhododendron cyanocarpum, revealed that these species diverged about 3.05 (2.21–5.03) million years ago. This divergence may have been caused by environmental changes that occurred after the late Pliocene, e.g., the Asian winter monsoon intensified, leading to a drier climate. Based on these findings, we recommend that R. meddianum be conserved through in situ, ex situ approaches and that its seeds be collected for germplasm., Highlights • Rhododendronmeddianum underwent a population bottleneck about 70,000 years ago, and diverged from Rhododendron cyanocarpum around 3.05 (2.21–5.03) million years ago.

Plant diversity monitoring is an essential basis for plant conservation and policy making, and is critical to the sustainable use and protection of biological resources. We reviewed the research progress on plant diversity monitoring, and proposed further research direction. Plant diversity monitoring is developing rapidly at a new situation, and enters a new era referring to intelligent, integration of macroscopic and microscopic, networked monitoring, big data, large-scale, multidisciplinary, all-dimensional, from species level to family level, community level or ecosystem level, and even the global level. The construction of biodiversity monitoring network promotes the uniform of essential biodiversity variables and networked monitoring. Internet information and database had become a main data source of plant diversity. There are many new challenges in plant diversity monitoring, including standardization, effective utilization and sharing of the monitoring data, as well as the monitoring for genetic diversity and individuals. Ecological monitoring would be large-scale, automated and standardized. Many things should be addressed in further research, including to improve the monitoring networks, to find innovative ways and build new models, to carry out monitoring at hotspots and give priority to important species as well as community or even larger scale, to pay more attention to the background investigation of plant resource.监测是植物保护工作的重要基础,也是管理者决策的重要依据,对生物资源的可持续利用和保护至关重要。本研究综述了植物多样性监测的进展,就未来的热点和方向进行了探讨。植物多样性监测正以全新的局面飞速发展,已经进入了智能化、宏观与微观结合、联网监测、大数据、大尺度、多学科、全方位、立体化、由物种水平扩展到科属水平、群落或生态系统层面的监测时代;生物多样性监测网络的建设促进了联网监测与核心监测指标体系的统一,网络资源成为植物多样性监测的大数据源。数据的标准化与有效利用、大数据共享、遗传多样性和个体物种水平监测是监测植物多样性的机遇和挑战。未来的生态监测是大尺度、智能化、统一化的监测,完善监测网络体系,寻找新方法、构建新模型,开展热点区域和优先物种监测,并兼顾群落或更大尺度,重视植物基础本底数据的收集,是今后监测的重点。.

Ceropegia jinshaensis D.T.Liu & Z.K.Wu (Asclepiadoideae, Apocynaceae), a new species from northwestern Yunnan along the upper Yangtze river of China, is described and illustrated. This species is similar to C. meleagris H. Huber, C. dorjei C. E. C. Fischer and C. aridicola W. W. Smith, but can be distinguished easily by its leaf shape and floral features, especially the corolla shape and size, the interior of corolla tube and coronal characters.

Plant Species with Extremely Small Populations, PSESP, is a conservation concept developed in China aimed at rescuing most threatened plant species of China. The PSESP conservation program was first implemented in Yunnan Province in 2005. Here, we review the development and importance of this concept. Current progress based on the Implementation Plan of Rescuing and Conserving China's PSESP (2011–2015) is highlighted. 120 species were targeted for priority conservation under this program. Based on the PSESP guidelines, several key national and provincial projects supporting practical conservation and research in conservation biology were initiated. While a number of conservation objectives were achieved, unexpected challenges have hindered the fulfillment of five goals that the Plan expected to accomplish by 2015. We provide examples of a successful methodology and the factors supporting these techniques, as well as describe the gaps between scientific research and conservation practices. Finally, we emphasize how interdisciplinary conservation efforts involving multi-stakeholder coalitions with representatives from research institutes, government agencies, non-governmental organizations and local communities should be encouraged to achieve successful PSESP conservation. While this review seeks to facilitate China's tremendous plant conservation efforts to help overcome existing and be prepared for future challenges, the PSESP approach could be valuable in other countries for the preservation of threatened plants.

Chloranthus flavus sp. nov., a new species from Guangxi Zhuang Autonomous Region in China, is described based on living organisms and type specimens. The new species is morphologically similar to Chloranthus nervosus Coll. et Hemsl. due to their similar flower and leaf characters. However, they can be easily distinguished by their habits, stems and color of stamen connectives. The main morphological features of the new species are described, and color photographs are provided.

Disporum xilingense is described from Sichuan, China. The new species is related to D. leucanthum and D. bodinieri, with which it shares similar terminal inflorescences, widely open and nodding flowers with tepals slightly saccate at the base. However, its narrowly lanceolate tepals 23–26 mm long with tapered lower part 5–6 mm long, stamens distinctly shorter than the tepals, and style equaling or slight longer than the tepals support recognition at the species rank. The new species is also similar to D. acuminatissimum in flower size and color, whereas D. xilingense differs by its acute apices of leaves and tepals, widely opening flowers, glabrous tepals only minutely papillate on the lower margin and inside, sharply narrowed and navicular tepal bases, stamens 14–16 mm long and style 24–26 mm long. Furthermore, data are reported to exclude D. leucanthum from the flora of China. The main morphological features of the new species are discussed and illustrations and an identification key are provided.