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Many species of Salvia have excellent ornamental, culinary, and medicinal values. Salvia daiguii, is an ornamental and highly medicinal perennial herb endemic to the prefecture‐level city of Zhangjiajie in Hunan Province, China, with a narrow geographical distribution. However, currently, it has only been assessed as a Critically Endangered species according to the IUCN classification criteria, but its conservation has not yet been studied. This study investigated the distribution and niche characteristics of S. daiguii, and compared the differences in growth, flowering characteristics, and soil nutrients between the wild and ex situ populations. We also analyzed the effects of soil nutrients on plant growth and flowering characteristics. During the survey, we found 274 individuals on a rock approximately 200 m from ZEFR1. Nevertheless, S. daiguii were still restricted in three populations, TNFP, TGM, and ZEFR in Zhangjiajie City, with a total of about 500 plants and less than 250 mature individuals. Our results show that aspects such as adverse environmental conditions, low seedling renewal rate, a lack of soil nutrients, and competition for the characteristic niche of this and other dominant plants in the natural community are the main ecological factors affecting the growth, flowering, and geographic distribution of S. daiguii. Based on the results of field surveys, we recommend that (1) S. daiguii be classified as Critically Endangered C2b and China's List of Plant Species with Extremely Small Populations. (2) Comprehensive conservation strategies were developed, such as the establishment of nature reserves, reintroduction, public education, and institutional development to provide management recommendations related to the conservation of S. daiguii and other endangered plants. [ABSTRACT FROM AUTHOR]

Abstract Many species of Salvia have excellent ornamental, culinary, and medicinal values. Salvia daiguii, is an ornamental and highly medicinal perennial herb endemic to the prefecture‐level city of Zhangjiajie in Hunan Province, China, with a narrow geographical distribution. However, currently, it has only been assessed as a Critically Endangered species according to the IUCN classification criteria, but its conservation has not yet been studied. This study investigated the distribution and niche characteristics of S. daiguii, and compared the differences in growth, flowering characteristics, and soil nutrients between the wild and ex situ populations. We also analyzed the effects of soil nutrients on plant growth and flowering characteristics. During the survey, we found 274 individuals on a rock approximately 200 m from ZEFR1. Nevertheless, S. daiguii were still restricted in three populations, TNFP, TGM, and ZEFR in Zhangjiajie City, with a total of about 500 plants and less than 250 mature individuals. Our results show that aspects such as adverse environmental conditions, low seedling renewal rate, a lack of soil nutrients, and competition for the characteristic niche of this and other dominant plants in the natural community are the main ecological factors affecting the growth, flowering, and geographic distribution of S. daiguii. Based on the results of field surveys, we recommend that (1) S. daiguii be classified as Critically Endangered C2b and China's List of Plant Species with Extremely Small Populations. (2) Comprehensive conservation strategies were developed, such as the establishment of nature reserves, reintroduction, public education, and institutional development to provide management recommendations related to the conservation of S. daiguii and other endangered plants.

Camellia fascicularis belongs to the family Theaceae and is a plant species with extremely small populations. It is also a second-class national protected plant in China. In recent years, the anti-inflammation, antioxidation, and antitumor effects of C. fascicularis polyphenols and flavonoids have been reported. However, changes in the soil chemistry and microbes after artificial cultivation of C. fascicularis have not been well studied. Therefore, three healthy plants from each different artificial planting year's plot (Age_3, Age_5, and Age_7) were selected, and the chemical properties of the rhizosphere soil and root endophytic microbial communities for different cultivation years of C. fascicularis were studied in Hekou County, China. The accumulation of pathogenic and beneficial microbes in the rhizosphere of C. fascicularis was also discussed. The results show that (1) the alpha diversity in rhizosphere soil was significantly higher than that in roots, and roots recruited more Actinobacteria, which might produce beneficial secondary metabolites for the plant; (2) the total nitrogen in the rhizosphere soil of C. fascicularis cultivated for 7 years was significantly higher than that in the soil cultivated for 3 years; (3) there was no significant difference in the alpha and beta diversity in the rhizosphere soil and root endophytes of C. fascicularis in different cultivation years; (4) there was no difference in the abundance of plant-growth-promoting rhizobacteria (PGPR) in either the rhizosphere soil or roots, but the number of PGPR in roots was higher than that in rhizosphere soil; and (5) the changes in pathogenic fungi and biocontrol fungi in rhizosphere soil were greater than those of endophytic fungi in roots. The results show that there are no significant differences in microbial communities among 3, 5, and 7 years, but the influence of the outside environment on the soil and fungi was greater than that of the roots and bacteria. These results can help us to understand the soil chemical and microbial community changes during the artificial cultivation of C. fascicularis and play an important role in its artificial conservation and breeding, as it is a plant species with extremely small populations. [ABSTRACT FROM AUTHOR]

Buddleja sessilifolia is a plant species with extremely small populations (PSESP) in southwest China. The trial of transplantation failed in our Buddleja outdoor garden, and only succeeded in the flowerpots of greenhouse. In this study, we conducted metagenomic analyses on microbial diversity in bulk soil from wild habitat of B. sessilifolia, the Buddleja garden and the B. sessilifolia pots of greenhouse, and meanwhile analyzed soil physicochemical properties. We aimed to uncover the related soil factors which may influence the transplantation of B. sessilifolia. Our results showed the bulk soil from the wild habitat of B. sessilifolia and the B. sessilifolia pots had significantly richer total potassium content than that from the Buddleja garden. Bacterial order Rhizobiales and archaeal class Nitrososphaeria showed a higher diversity in both the wild habitat and the pot than the garden. Furthermore, soil total potassium content was the most correlated to bacterial community structure of the bulk soil, while soil total nitrogen content and total phosphorus content were most important to archaeal and fungal community structures. We accordingly inferred that B. sessilifolia had a high demand on potassium and microbial Rhizobiales and Nitrososphaeria in soil for its survival. Our findings will contribute to the ex-situ conservation of B. sessilifolia. [ABSTRACT FROM AUTHOR]

Vatica guangxiensis X. L. Mo (Dipterocaceae) is a valuable timber tree species endemic to China and a typical plant species with extremely small populations (PSESP). To understand the pattern variations in the genetic diversity of V. guangxiensis during natural regeneration, large-scale genome-wide SNPs were developed using genotyping by sequencing (GBS) to assess genetic diversity and population structure and to infer demographic history. The observed heterozygosity (HO), expected heterozygosity (HE), and nucleotide diversity (π) of V. guangxiensis were 0.1810, 0.2128, and 0.2178, respectively, demonstrating a low genetic diversity characteristic similar to most PSESP. However, further analysis of trees at different periods of natural regeneration revealed that both small trees and medium trees had lower genetic diversity than big trees. One important cause of the low and declining genetic diversity of V. guangxiensis may be the inbreeding that is forced due to the very small population size. Notably, a rare genetic component was detected in the genomes of several individuals in the medium tree and small tree groups, which may have been derived from other big trees that have died. In addition, the Tajima’D value (0.0689) and Stairway plot revealed a population bottleneck along with a continuous decline in the effective population size of V. guangxiensis since the last glacial period. These findings expand the understanding of the evolutionary history of the diversity of PSESP and the variation patterns in their genetic diversity, thus providing a basis to develop an effective conservation strategy.

Camellia fascicularis belongs to the family Theaceae and is a plant species with extremely small populations. It is also a second-class national protected plant in China. In recent years, the anti-inflammation, antioxidation, and antitumor effects of C. fascicularis polyphenols and flavonoids have been reported. However, changes in the soil chemistry and microbes after artificial cultivation of C. fascicularis have not been well studied. Therefore, three healthy plants from each different artificial planting year’s plot (Age_3, Age_5, and Age_7) were selected, and the chemical properties of the rhizosphere soil and root endophytic microbial communities for different cultivation years of C. fascicularis were studied in Hekou County, China. The accumulation of pathogenic and beneficial microbes in the rhizosphere of C. fascicularis was also discussed. The results show that (1) the alpha diversity in rhizosphere soil was significantly higher than that in roots, and roots recruited more Actinobacteria, which might produce beneficial secondary metabolites for the plant; (2) the total nitrogen in the rhizosphere soil of C. fascicularis cultivated for 7 years was significantly higher than that in the soil cultivated for 3 years; (3) there was no significant difference in the alpha and beta diversity in the rhizosphere soil and root endophytes of C. fascicularis in different cultivation years; (4) there was no difference in the abundance of plant-growth-promoting rhizobacteria (PGPR) in either the rhizosphere soil or roots, but the number of PGPR in roots was higher than that in rhizosphere soil; and (5) the changes in pathogenic fungi and biocontrol fungi in rhizosphere soil were greater than those of endophytic fungi in roots. The results show that there are no significant differences in microbial communities among 3, 5, and 7 years, but the influence of the outside environment on the soil and fungi was greater than that of the roots and bacteria. These results can help us to understand the soil chemical and microbial community changes during the artificial cultivation of C. fascicularis and play an important role in its artificial conservation and breeding, as it is a plant species with extremely small populations.

Abstract Background Amorphophallus albus P. Y. Liu & J. F. Chen (Araceae) is a plant species with extremely small populations (PSESP) and an important economic crop endemic to dry-hot valleys along the Jinsha River. In order to gain information for sustaining the development and conservation of A. albus, we studied the genetic diversity and population structure of this species using microsatellite markers (SSR). In this study, we analysed 364 individuals belonging to 24 populations, including four wild populations and three ex-situ cultivated populations, collected in the provinces Yunnan, Sichuan and Hubei. Results The population genetic analyses indicated that A. albus possesses moderate genetic diversity with the percentage of polymorphic loci (PPL) from 69.23 to 100%, an expected heterozygosity (He) of 0.504 and an average Shannon’s Information Index (I) 0.912. Analysis of molecular variance (AMOVA) indicated that most of the variance (71%) resided within populations and the estimated gene flow (Nm) was 0.61. The results of UPGMA cluster tree, STRUCTURE analyses together with the Mantel test (R2 = 0.352, P

Magnolia sinica (Magnoliaceae) is a highly threatened tree endemic to southeast Yunnan, China. In this study, we generated for the first time a high-quality chromosome-scale genome sequence from M. sinica, by combining Illumina and ONT data with Hi-C scaffolding methods. The final assembled genome size of M. sinica was 1.84 Gb, with a contig N50 of ca. 45 Mb and scaffold N50 of 92 Mb. Identified repeats constituted approximately 57% of the genome, and 43,473 protein-coding genes were predicted. Phylogenetic analysis shows that the magnolias form a sister clade with the eudicots and the order Ceratophyllales, while the monocots are sister to the other core angiosperms. In our study, a total of 21 individuals from the 5 remnant populations of M. sinica, as well as 22 specimens belonging to 8 related Magnoliaceae species, were resequenced. The results showed that M. sinica had higher genetic diversity (θw = 0.01126 and θπ = 0.01158) than other related species in the Magnoliaceae. However, population structure analysis suggested that the genetic differentiation among the 5 M. sinica populations was very low. Analyses of the demographic history of the species using different models consistently revealed that 2 bottleneck events occurred. The contemporary effective population size of M. sinica was estimated to be 10.9. The different patterns of genetic loads (inbreeding and numbers of deleterious mutations) suggested constructive strategies for the conservation of these 5 different populations of M. sinica. Overall, this high-quality genome will be a valuable genomic resource for conservation of M. sinica., (© The Author(s) 2024. Published by Oxford University Press GigaScience.)

The complete plastid genome of Rhododendron griersonianum, a critically endangered plant species with extremely small populations, was obtained using Illumina HiSeq X Ten and ONT PromethION sequencing. The full length of the plastid genome is 206,467 bp with an overall GC content of 35.8%, which encodes 118 unique genes, including 78 protein-coding genes, 36 tRNA and 4 rRNA genes. Phylogenetic analysis revealed that all Rhododendron species formed a monophyletic clade. This study provides a valuable reference and will facilitate future studies related to the general characteristics and evolution of plastid genomes in the genus Rhododendron.

Magnolia sinica is one of the most threatened trees endemic to Southeast Yunnan. Based on our investigations, only 52 individuals and eight populations are found in the wild. M. sinica has been categorized as Critically Endangered on the IUCN Red List and identified as a “Plant Species with Extremely Small Populations (PSESP)”. Its fruit/seed set is very low and seedlings are rarely found in the wild. It is hypothesized that it may encounter obstacles to reproductive success. This study, therefore, focuses on its reproductive biology, knowledge of which is essential for effective conservation. Flowers of this species are protogynous and nocturnal, and possess a two-day rhythm of sexual presentation. For the first night of anthesis, the flowers are in the pistillate stage during which tepals open at dusk and close approx. 1 h later (except for the open outer ones). They remain closed until the next afternoon, when flowers, now in the staminate stage, re-open and remain so until the tepals drop. Nocturnal beetles enter into the flowers and remain trapped throughout the night as the flower closes, during which time they feed on tepals. Pollen-gathering bees are found to visit the re-opened flowers and the beetles are released during this stage. Two species of Pleocomidae and Curculionidae beetles appear to be effective pollinators. M. sinica is a self-compatible, pollinator-dependent species, and its fruit/seed set can be significantly increased by hand-pollination. No functional seed dispersers have been found in its extant natural habitats. These findings suggest that it may face both pollination and seed disperser insufficiencies in its current fragmented habitats, which may account for its low regeneration. Here we propose conservation strategies based on our findings.

The Chinese flora occupies a unique position in global plant diversity, but is severely threatened. Although biodiversity conservation in China has made significant progress over the past decades, many wild plant species have extremely small population sizes and therefore are in extreme danger of extinction. The concept of plant species with extremely small populations (PSESPs), recently adopted and widely accepted in China, lacks a detailed description of the methodology appropriate for conserving PSESPs. Strategies for seed sampling, reintroduction, protecting PSESP locations, managing interactions with the local human population, and other conservation aspects can substantially differ from those commonly applied to non-PSESPs. The present review is an attempt to provide a detailed conservation methodology with realistic and easy-to-follow guidelines for PSESPs in China.

The concept of Plant Species with Extremely Small Populations (PSESP) has been employed to guide conservation of threatened plant species in China. Climate change has a high potential to threaten PSESP. As a result, it is necessary to integrate climate change effects on PSESP into conservation planning in China. Here, ecological niche modelling is used to project current and future habitat distributions of six PSESP in China under climate change scenarios and conservation planning software is applied to identify priority conservation areas (PCAs) for these PSESP based on habitat distributions. These results were used to provide proposals for in-situ and ex-situ conservation measures directed at PSESP. It was found that annual precipitation was important for habitat distributions for all six PSESP (with the percentage contribution to habitat distributions ranging from 18.1 % to 74.9 %) and non-climatic variables including soil and altitude have a large effect on habitat suitability of PSESP. Large quantities of PCAs occurred within some provincial regions for these six PSESP (e.g. Sichuan and Jilin for the PSESP Cathaya argyrophylla, Taxus cuspidata, Annamocarya sinensis and Madhuca pasquieri), indicating that these are likely to be appropriate areas for in-situ and ex-situ conservation measures directed at these PSESP. Those nature reserves with large quantities of PCAs were identified as promising sites for in-situ conservation measures of PSESP; such reserves include Yangzie and Dongdongtinghu for C. argyrophylla, Songhuajiangsanhu and Changbaishan for T. cuspidata and Shiwandashanshuiyuanlian for Tsoongiodendron odorum. These results suggest that existing seed banks and botanical gardens occurring within identified PCAs should allocate more resources and space to ex-situ conservation of PSESP. In addition, there should be additional botanical gardens established for ex-situ conservation of PSESP in PCAs outside existing nature reserves. To address the risk of negative effects of climate change on PSESP, it is necessary to integrate in-situ and ex-situ conservation as well as climate change monitoring in PSESP conservation planning. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The complete plastid genome of Rhododendron griersonianum , a critically endangered plant species with extremely small populations, was obtained using Illumina HiSeq X Ten and ONT PromethION sequencing. The full length of the plastid genome is 206,467 bp with an overall GC content of 35.8%, which encodes 118 unique genes, including 78 protein-coding genes, 36 tRNA and 4 rRNA genes. Phylogenetic analysis revealed that all Rhododendron species formed a monophyletic clade. This study provides a valuable reference and will facilitate future studies related to the general characteristics and evolution of plastid genomes in the genus Rhododendron ., Competing Interests: The authors report no conflict of interest., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Background Acer yangbiense is a newly described critically endangered endemic maple tree confined to Yangbi County in Yunnan Province in Southwest China. It was included in a programme for rescuing the most threatened species in China, focusing on "plant species with extremely small populations (PSESP)". Findings We generated 64, 94, and 110 Gb of raw DNA sequences and obtained a chromosome-level genome assembly of A. yangbiense through a combination of Pacific Biosciences Single-molecule Real-time, Illumina HiSeq X, and Hi-C mapping, respectively. The final genome assembly is ∼666 Mb, with 13 chromosomes covering ∼97% of the genome and scaffold N50 sizes of 45 Mb. Further, BUSCO analysis recovered 95.5% complete BUSCO genes. The total number of repetitive elements account for 68.0% of the A. yangbiense genome. Genome annotation generated 28,320 protein-coding genes, assisted by a combination of prediction and transcriptome sequencing. In addition, a nearly 1:1 orthology ratio of dot plots of longer syntenic blocks revealed a similar evolutionary history between A. yangbiense and grape, indicating that the genome has not undergone a whole-genome duplication event after the core eudicot common hexaploidization. Conclusion Here, we report a high-quality de novo genome assembly of A. yangbiense , the first genome for the genus Acer and the family Aceraceae. This will provide fundamental conservation genomics resources, as well as representing a new high-quality reference genome for the economically important Acer lineage and the wider order of Sapindales. [ABSTRACT FROM AUTHOR]

Hibiscus aridicola is an endangered ornamental shrub of the family Malvaceae that is endemic to the dry-hot valleys of Jinsha River in southwestern China. This species is a typical plant species with extremely small populations (PSESP). To support and monitor future conservation, develop management measures, and genotype this species, we performed extensive field studies together with genetic analyses. Specifically, we screened eleven microsatellite loci of 69 individuals of H. aridicola from four accessions. The population genetics analyses indicated that H. aridicola possesses high genetic diversity at both the population (0.6962-0.7293) and species level (0.7837) compared to other endemic/endangered species in China. The low differentiation of populations (Fst = 0.0971) and the high gene flow between populations of H. aridicola (Nm = 2.3236) could be due to its distribution along rivers in the hot-valleys of the Jinsha River and the wind-mediated dispersal of its seeds. Furthermore, the genetic diversity of H. aridicola is slightly positively correlated with geographic distance. Two populations are undergoing a genetic bottleneck, and require more specific attention from conservationists. Additionally, our analyses of the population genetics of H. aridicola demonstrate that the declines in populations are not the result of the internal genetics of these populations but due to external human activities over the past decades., (© 2019 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.)

Magnolia sinica is one of the most threatened trees endemic to Southeast Yunnan. Based on our investigations, only 52 individuals and eight populations are found in the wild. M. sinica has been categorized as Critically Endangered on the IUCN Red List and identified as a "Plant Species with Extremely Small Populations (PSESP)". Its fruit/seed set is very low and seedlings are rarely found in the wild. It is hypothesized that it may encounter obstacles to reproductive success. This study, therefore, focuses on its reproductive biology, knowledge of which is essential for effective conservation. Flowers of this species are protogynous and nocturnal, and possess a two-day rhythm of sexual presentation. For the first night of anthesis, the flowers are in the pistillate stage during which tepals open at dusk and close approx. 1 h later (except for the open outer ones). They remain closed until the next afternoon, when flowers, now in the staminate stage, re-open and remain so until the tepals drop. Nocturnal beetles enter into the flowers and remain trapped throughout the night as the flower closes, during which time they feed on tepals. Pollen-gathering bees are found to visit the re-opened flowers and the beetles are released during this stage. Two species of Pleocomidae and Curculionidae beetles appear to be effective pollinators. M. sinica is a self-compatible, pollinator-dependent species, and its fruit/seed set can be significantly increased by hand-pollination. No functional seed dispersers have been found in its extant natural habitats. These findings suggest that it may face both pollination and seed disperser insufficiencies in its current fragmented habitats, which may account for its low regeneration. Here we propose conservation strategies based on our findings.

The Chinese flora occupies a unique position in global plant diversity, but is severely threatened. Although biodiversity conservation in China has made significant progress over the past decades, many wild plant species have extremely small population sizes and therefore are in extreme danger of extinction. The concept of plant species with extremely small populations (PSESPs), recently adopted and widely accepted in China, lacks a detailed description of the methodology appropriate for conserving PSESPs. Strategies for seed sampling, reintroduction, protecting PSESP locations, managing interactions with the local human population, and other conservation aspects can substantially differ from those commonly applied to non-PSESPs. The present review is an attempt to provide a detailed conservation methodology with realistic and easy-to-follow guidelines for PSESPs in China.