Clear species boundaries are crucial for plans and actions on biodiversity conservation. However, morphological similarities among allied species can result in taxonomic difficulties, thus impeding conservation efforts. In China, Cinnamomum japonicum Siebold is a well-known endangered plant, yet suffers from longstanding taxonomic issues. Here, we explicitly evaluate whether C. japonicum, C. chenii, and C. chekiangense are the same phylogenetic species on the basis of a multi-individual sampling strategy. We identified three sets of low-copy orthologous genes from 19 Lauraceae taxa for phylogenetic inferences. Both the concatenation and coalescent-based phylogenies supported that C. chenii individuals were embedded in the C. japonicum clade, indicating these two taxa are conspecific. Meanwhile, C. chekiangense accessions formed a monophyly which was not sister to C. japonicum. This result, together with the morphological differences that the leaves of C. japonicum are glabrous with a faveolate pattern of venation while those of C. chekiangense have trichomes and inevident lateral veins, led us to consider both as two distinct species. Based on 17 728 neutral single nucleotide polymorphisms (SNPs), the ADMIXTURE analysis suggested that the Chinese C. japonicum populations in Zhoushan Archipelago (=C. chenii) were genetically differentiated from the Japanese and Korean ones. Furthermore, ecological niche modeling predicted that the present distribution area of Chinese C. japonicum is likely to be unsuitable under global warming scenarios. Together with its limited distribution and genetic uniqueness, we recommend that Chinese C. japonicum deserves conservation priorities.

Coniferous forests are under severe threat of the rapid anthropogenic climate warming. Abies (firs), the fourth-largest conifer genus, is a keystone component of the boreal and temperate dark-coniferous forests and harbors a remarkably large number of relict taxa. However, the uncertainty of the phylogenetic and biogeographic history of Abies significantly impedes our prediction of future dynamics and efficient conservation of firs. In this study, using 1,533 nuclear genes generated from transcriptome sequencing and a complete sampling of all widely recognized species, we have successfully reconstructed a robust phylogeny of global firs, in which four clades are strongly supported and all intersectional relationships are resolved, although phylogenetic discordance caused mainly by incomplete lineage sorting and hybridization was detected. Molecular dating and ancestral area reconstruction suggest a Northern Hemisphere high-latitude origin of Abies during the Late Cretaceous, but all extant firs diversified during the Miocene to the Pleistocene, and multiple continental and intercontinental dispersals took place in response to the late Neogene climate cooling and orogenic movements. Notably, four critically endangered firs endemic to subtropical mountains of China, including A. beshanzuensis, A. ziyuanensis, A. fanjingshanensis and A. yuanbaoshanensis from east to west, have different origins and evolutionary histories. Moreover, three hotspots of species richness, including western North America, central Japan, and the Hengduan Mountains, were identified in Abies. Elevation and precipitation, particularly precipitation of the coldest quarter, are the most significant environmental factors driving the global distribution pattern of fir species diversity. Some morphological traits are evolutionarily constrained, and those linked to elevational variation (e.g., purple cone) and cold resistance (e.g., pubescent branch and resinous bud) may have contributed to the diversification of global firs. Our study sheds new light on the spatiotemporal evolution of global firs, which will be of great help to forest management and species conservation in a warming world.

Understanding genome-wide diversity, inbreeding, and the burden of accumulated deleterious mutations in small and isolated populations is essential for predicting and enhancing population persistence and resilience. However, these effects are rarely studied in limestone karst plants. Here, we re-sequenced the nuclear genomes of 62 individuals of the Begonia masoniana complex (B. liuyanii, B. longgangensis, B. masoniana and B. variegata) and investigated genomic divergence and genetic load for these four species. Our analyses revealed four distinct clusters corresponding to each species within the complex. Notably, there was only limited admixture between B. liuyanii and B. longgangensis occurring in overlapping geographic regions. All species experienced historical bottlenecks during the Pleistocene, which were likely caused by glacial climate fluctuations. We detected an asymmetric historical gene flow between group pairs within this timeframe, highlighting a distinctive pattern of interspecific divergence attributable to karst geographic isolation. We found that isolated populations of B. masoniana have limited gene flow, the smallest recent population size, the highest inbreeding coefficients, and the greatest accumulation of recessive deleterious mutations. These findings underscore the urgency to prioritize conservation efforts for these isolated population. This study is among the first to disentangle the genetic differentiation and specific demographic history of karst Begonia plants at the whole-genome level, shedding light on the potential risks associated with the accumulation of deleterious mutations over generations of inbreeding. Moreover, our findings may facilitate conservation planning by providing critical baseline genetic data and a better understanding of the historical events that have shaped current population structure of rare and endangered karst plants.

The identification and understanding of cryptic intraspecific evolutionary units (lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered species. However, the factors driving the evolution and maintenance of these intraspecific lineages in most endangered species remain poorly understood. In this study, we conducted resequencing of 77 individuals from 22 natural populations of Davidia involucrata, a “living fossil” dove tree endemic to central and southwest China. Our analysis revealed the presence of three distinct local lineages within this endangered species, which emerged approximately 3.09 and 0.32 million years ago. These divergence events align well with the geographic and climatic oscillations that occurred across the distributional range. Additionally, we observed frequent hybridization events between the three lineages, resulting in the formation of hybrid populations in their adjacent as well as disjunct regions. These hybridizations likely arose from climate-driven population expansion and/or long-distance gene flow. Furthermore, we identified numerous environment-correlated gene variants across the total and many other genes that exhibited signals of positive evolution during the maintenance of two major local lineages. Our findings shed light on the highly dynamic evolution underlying the remarkably similar phenotype of this endangered species. Importantly, these results not only provide guidance for the development of conservation plans but also enhance our understanding of evolutionary past for this and other endangered species with similar histories.

珠芽胎生繁殖是蕨类植物孢子繁殖的有益补充，丰富了植物的繁殖再生系统，影响着种群遗传多样性和对环境的适应能力。该研究以国家Ⅰ级重点保护野生植物光叶蕨（Cystopteris chinensis）为对象，通过形态学与解剖学方法，探究其羽片后面不明突起——珠芽的形态与解剖特征，揭示其生殖结构和发育过程，追溯珠芽胎生起源和生态适应机制。结果显示：（1）珠芽和孢子囊群同期出现在光叶蕨羽片背面末级细脉中部，只是珠芽位于顶端裂片。珠芽形成包括启动期、膨大期和成熟期3个时期，由黄绿色球状体逐渐成长为深绿色纺锤状，基部变黑形成离层时成熟。（2）珠芽起源于维管束鞘延伸区的薄壁细胞，不断分裂生长形成珠芽原基，逐渐突破叶下表皮形成圆球形珠芽；随着珠芽不断膨大，中下部细胞分化形成贮藏细胞和维管束，顶端分化出生长点形成芽。（3）极少数珠芽在叶片上可直接萌动形成新的自养个体。成熟珠芽掉落在土壤内1周后开始萌发，基部长出圆柱形根，顶部萌发出拳芽。残留珠芽第2年仍可萌发形成新叶，与茎芽产生的叶片形态有别。

Global climate change has increased concerns regarding biodiversity loss. However, many key conservation issues still required further research, including demographic history, deleterious mutation load, adaptive evolution, and putative introgression. Here we generated the first chromosome-level genome of the endangered Chinese hazelnut, Corylus chinensis, and compared the genomic signatures with its sympatric widespread C. kwechowensis-C. yunnanensis complex. We found large genome rearrangements across all Corylus species and identified species-specific expanded gene families that may be involved in adaptation. Population genomics revealed that both C. chinensis and the C. kwechowensis-C. yunnanensis complex had diverged into two genetic lineages, forming a consistent pattern of southwestern-northern differentiation. Population size of the narrow southwestern lineages of both species have decreased continuously since the late Miocene, whereas the widespread northern lineages have remained stable (C. chinensis) or have even recovered from population bottlenecks (C. kwechowensis-C. yunnanensis complex) during the Quaternary. Compared with C. kwechowensis-C. yunnanensis complex, C. chinensis showed significantly lower genomic diversity and higher inbreeding level. However, C. chinensis carried significantly fewer deleterious mutations than C. kwechowensis-C. yunnanensis complex, as more effective purging selection reduced the accumulation of homozygous variants. We also detected signals of positive selection and adaptive introgression in different lineages, which facilitated the accumulation of favorable variants and formation of local adaptation. Hence, both types of selection and exogenous introgression could have mitigated inbreeding and facilitated survival and persistence of C. chinensis. Overall, our study provides critical insights into lineage differentiation, local adaptation, and the potential for future recovery of endangered trees.

Understanding the driving forces of speciation is a central question in evolutionary biology. Cycas bifida (Dyer) K. D. Hill and Cycas micholitzii Dyer are two morphologically similar Cycas (Cycadaceae) species with deeply pectinate megasporophylls and dichotomously divided leaflets. Geographically, they are isolated by the Red River Fault Zone (RRFZ), which acts as a biogeographical barrier for many Cycas species. In this study, we investigated the divergence, genetic diversity, genetic structure, and demographic history of C. bifida and C. micholitzii to uncover the speciation mechanisms for the two endangered species. Results revealed high historical gene flow but low contemporary gene flow between the two species, with a deep divergence occurring in the Late Miocene. The long-term geographical isolation and ecological niche differentiation were identified as important factors in driving the divergence of the two species, supported by significant isolation by distance testing, barrier analysis, and niche consistency detection. Geographical isolation by the RRFZ played a pivotal role in facilitating their divergence by constraining gene flow. Conservation genetic analyses indicated high genetic diversity within both species, coupled with disparate responses to Pleistocene climate fluctuations: C. micholitzii experienced population expansion, while C. bifida displayed a mild bottleneck effect. To ensure the protection and long-term sustainability of two threatened species, relevant conservation guidelines were proposed based on the assessment of their genetic diversity and structure. This study furnishes valuable insights into the mechanisms underpinning species divergence and delivers actionable recommendations for cycad conservation.

为探究海南吊罗山山铜材（Chunia bucklandioides）种群结构与动态特征，以当地山铜材野生种群为研究对象，将种群集中分布区域设为典型样地并开展样地调查，以空间代替时间构建种群年龄结构，采用动态量化分析、绘制存活曲线、计算生存函数等方法分析现有种群结构特点和动态特征，并通过时间序列预测模型推测种群未来发展趋势。结果表明：（1）吊罗山山铜材种群年龄结构接近不规则金字塔型，动态量化分析显示该种群为增长型种群，但第Ⅰ~Ⅲ龄级间存在衰退现象，种群增长性弱，稳定性差，受外界干扰敏感度高，有向稳定型种群转变的趋势。（2）随龄级增加，山铜材标准化存活个体数量减少，生命期望降低，死亡率和消失率总体呈上升趋势，存活曲线趋近于Deevey-Ⅱ型。（3）生存分析显示吊罗山山铜材种群具有前期增长、中期稳定、后期衰退的特点。（4）经过未来2、4、6龄级时间后，Ⅰ~Ⅲ龄级个体数量将逐渐减少，Ⅳ~Ⅶ龄级个体数量少量增加，幼龄苗木自我更新能力不足，种群存在规模收缩和衰退的风险。研究表明，生境碎片化、分布范围小、植株结实量少和幼龄个体不足是导致吊罗山山铜材濒危的主要因素，建议通过设立自然保护小区、辅助种子入土萌发、加快人工培育技术研究、人工扩大种群规模与数量和加强基础研究等方式，促进山铜材种群复壮与更新。

运用石蜡切片技术对小勾儿茶（Berchemiella wilsonii）进行生殖生物学观察，探讨其大小孢子发生和雌雄配体发育过程是否存在濒危环节。结果显示：小勾儿茶的花具5个雄蕊和4个花药室，成熟的花药壁由花药内壁（1层）、中层（2层）和绒毡层（1层）组成。绒毡层发育正常，细胞排列整齐规则，与中层细胞联系紧密，细胞中常多核。小孢子母细胞在减数分裂时胞质分裂方式为同时型，四分体主要以四面体形式存在，花粉粒在成熟时为二细胞型、圆形或椭圆形，多数有3根萌发管。花药发育过程中绒毡层发育存在少量异常，花粉存在少量败育。小勾儿茶子房2室，只发育1室。胚珠为倒生的双珠被和厚珠心，合点端大孢子发育成功能性大孢子，经过3次有丝分裂，进一步发育成具有7个细胞和8个核的胚囊，胚囊发育方式为蓼型。子房中的胚珠发育基本一致。小勾儿茶大小孢子发生和雌雄配子体发育基本正常，不是导致其结实率低的原因。

植物间的相互作用已成为评估濒危植物适应能力的研究热点,但其潜在的分子基础仍不清晰。本研究对比分析了浇灌灯台树(Cornusβcontroversa )叶水提物(0.025 gβmL^-1)和枝水提物(0.1 gβmL^-1)后,珙桐(Davidiaβinvolucrata)幼苗的形态、生物量、DiSOC1-b和DiCCoAOMT1基因表达量的差异。结果表明：灯台树叶水提物显著抑制珙桐幼苗形态和生物量的积累,而枝水提物显著促进珙桐幼苗形态和生物量的积累。此外,灯台树叶水提物处理后DiSOC1-b基因表达显著下调,DiCCoAOMT1基因表达显著上调。而灯台树枝水提物处理后,DiSOC1-b基因在珙桐叶和茎中表达显著上调,DiCCoAOMT1基因在珙桐根中的表达显著下调。DiSOC1-b表达量与珙桐幼苗大部分形态性状和总生物量呈正相关(P < 0.05),DiCCoAOMT1表达量与大部分形态性状呈负相关(P < 0.05)。上述结果表明,灯台树叶、枝水提物具有相反的化感效应,并影响珙桐幼苗生长相关基因(DiSOC1-b)和环境适应性相关基因(DiCCoAOMT1)的表达水平。

The recent development of genetic methods has facilitated the identification of cryptic species across different groups of organisms, including plants. However, next-generation sequencing has rarely been used to study cryptic speciation in plants, especially in bryophytes, organisms with a dominant haploid life phase. The ability to capture variation across the whole genome makes this method an effective tool for distinguishing cryptic lineages. We have focused on the genetic structure of the moss Meesia triquetra along the Alps-to-Scandinavia transect. We detected the presence of the two genetically critically different lineages of M. triquetra in Europe. These lineages overlap in both morphological characters of the gametophyte and distribution ranges. However, they considerably differ in ecological preferences to groundwater pH. While lineage 1 occupied alkaline to subneutral fens, lineage 2 occurred in fens saturated with neutral to acidic water. We consider the entities cryptic species with respect to genetic and ecological differences but the absence of morphological features necessary for determining the entities. We hypothesize that fragmentation of the ancestral population of the moss in geographically isolated refugia differing in the commonness of acidic and alkaline substrates led to consequent long-term adaptation to different environmental conditions, then drove diversification in M. triquetra.

Andromonoecy is a rare sexual system in plants. The function of additional male flowers in andromonoecious species has been widely discussed; however, few studies have taken offspring fitness into account. In addition, little is known about the mechanisms that maintain andromonoecy in autogamous species. In this study, we compared morphology, pollinator preference, pollen production and export, siring ability, natural siring success, hundred seed dry weight, and seed germination rates between male and hermaphroditic flowers in an endangered autogamous andromonoecious species, Sagittaria guayanensis. Male flowers, which are larger than hermaphroditic flowers, required fewer resources to produce. Pollinators visited male flowers more frequently than they visited hermaphroditic flowers. In addition, pollen production and export were higher in male flowers. Hand pollination demonstrated that siring ability did not differ between flower type. However, the natural siring success of male flowers was triple that of hermaphroditic flowers. The seeds sired by male flowers performed better than those sired by hermaphroditic flowers, with greater dry weight and higher germination rate. In conclusion, male flowers may be superior pollen donors for outcrossing. The maintenance of andromonoecy in S. guayanensis may result from the better performance of male flowers in male function compared to that of hermaphroditic flowers.

某些植物在没有外部刺激的情况下会在叶面上产生不同颜色的斑纹，即植物的斑叶现象。尽管之前的研究指出斑叶现象可能具有不同的功能，但未能解释某些物种内部的叶斑多态性。本研究以濒危的玉龙杓兰(Cypripedium forrestii)为研究对象，其同时存在斑叶和无斑叶两种个体。通过比较微观形态结构、光合作用潜力、差异表达基因(DEGs)和叶片被取食情况等数据，发现玉龙杓兰的斑叶现象不是病理性的，也不影响其光合作用潜力。叶斑的存在显著减少了食草动物的损害。无斑个体被食草动物取食的概率和叶面积损失显著更高，且在干旱年份中更明显，进而使得斑叶个体在干旱环境中可能具有更大的生长优势，而无斑叶个体在正常年份可能具有更大的成本效益。上述研究结果表明，具有不同叶斑形态的个体可能受到不同环境的选择，玉龙杓兰叶斑二态性可能是长期气候波动下平衡选择的结果。

Preserving genetic diversity is crucial for the long-term survival of wild plant species, yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation. Here, we present a comparative genomic study of the critically endangered Oreocharis esquirolii (Gesneriaceae) and its widespread congener O. maximowiczii. We assembled and annotated chromosome-level reference genomes for both species and generated whole-genome resequencing data from 28 O. esquirolii and 79 O. maximowiczii individuals. Our analyses reveal substantially lower genetic diversity and higher inbreeding in O. esquirolii, despite its overall reduced mutational burden. Notably, O. esquirolii exhibits an elevated proportion of strongly deleterious mutations relative to O. maximowiczii, suggesting that limited opportunities for purging have allowed these variants to accumulate. These contrasting genomic profiles likely reflect divergent demographic histories, with O. esquirolii having experienced severe bottlenecks and protracted population decline. Collectively, our findings highlight the critically endangered status of O. esquirolii, characterized by diminished genetic diversity, pronounced inbreeding, and reduced ability to eliminate deleterious alleles. This study provides valuable genomic resources for the Gesneriaceae family and underscores the urgent need for targeted conservation measures, including habitat protection and ex situ preservation efforts, to mitigate the extinction risk facing O. esquirolii and potentially other threatened congeners.

为建立濒危植物岩生鼠尾草（Salvia petrophila）的组培快繁体系，对岩生鼠尾草成熟种子消毒及萌发、基部带腋芽茎段继代增殖、无菌苗茎段愈伤组织诱导及分化、不定芽生根、炼苗移栽进行研究。结果表明：（1）岩生鼠尾草种子的适宜消毒方法为75%乙醇溶液处理30 s，5%次氯酸钠（NaClO）溶液消毒8 min，种子发芽率为40.83%。（2）种子萌发适宜培养基为MS+1.0 mg⋅L^-1 6-BA+0.1 mg⋅L^-1 NAA，发芽率为71.12%。（3）基部带腋芽茎段继代增殖适宜培养基为MS+1.0 mg⋅L^-1 6-BA+0.1 mg⋅L^-1 NAA，增殖系数为5.5。（4）无菌苗茎段愈伤组织诱导适宜培养基为MS+1.0 mg⋅L^-1 6-BA+1.0 mg⋅L^-1 2，4-D，诱导率高达97.10%；愈伤组织适宜分化培养基为MS+1.5 mg⋅L^-1 6-BA+0.1 mg⋅L^-1 NAA。（5）岩生鼠尾草不定芽生根适宜培养基为1/2MS+1.0 mg⋅L^-1 NAA，生根系数高达99.11%。（6）泥炭土、珍珠岩和蛭石体积比为1∶1∶1的混合基质为适宜栽培基质，移栽成活率高达85.5%。研究结果可为岩生鼠尾草的保护和利用奠定技术基础，同时也可为鼠尾草属其他植物的繁殖技术提供新的研究思路。

为了研究珍稀濒危植物沙冬青（Ammopiptanthus mongolicus）受到的竞争影响，选择沙冬青与霸王（Zygophyllum xanthoxylum）群落交错区，利用Hegyi单木竞争模型，通过对25株沙冬青对象木的调查，分析沙冬青的种内与种间竞争关系。结果表明：沙冬青的种内和种间竞争强度分别占总竞争强度（341.32）的5.09%和94.91%，说明沙冬青的竞争主要来源于种间。群落交错区内沙冬青的竞争木种类较多，竞争强度由大到小依次为内蒙古旱蒿（Artemisia xerophytica）、矮脚锦鸡儿（Caragana brachypoda）、霸王、猫头刺（Oxytropis aciphylla）、沙冬青、长叶红砂（Reaumuria trigyna）、驼绒藜（Krascheninnikovia ceratoides）、红砂（Reaumuria soongarica）、绵刺（Potaninia mongolica）、戈壁天门冬（Asparagus gobicus）。种间竞争指数和总竞争指数与沙冬青冠幅之间的关系均近似服从幂函数关系，竞争强度随对象木冠幅的增加而减小。当对象木的冠幅小于1.0 m时，受到的竞争压力较大，所得的模型能很好地反映沙冬青受到的竞争强度。