Cryptic divergences and repeated hybridizations within the endangered “living fossil” dove tree(Davidia involucrata) revealed by whole genome resequencing

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.

Living characteristics of rare and endangered species Davidia involucrata

Dovetree (Davidia involucrate), one of the first-class protective plants in China, is a relic species of paleotropical kingdom in Tertiary period, belonging toDavidiaceae with a single genus. In recent years, the increase of regional developing projects has led to a sharp decrease of this ancient and rare plant in naturally distributed habitats and natural population. In this paper, the biological and ecological characteristics of Dovetree were described, and the geographically distributed condition of this species in different geologic periods as well as the major reasons for dynamic changes of its population were systematically analyzed in accordance with field researches and references. The investigations conducted in different years by setting up standard sample plots showed that the population number of Dovetree increased yearly in the areas without human interference but decreased yearly in the areas with human interference. With the increase of population density and human activities decreased as the logarithmic curve:Y=?100.7ln(x)+178.09, and it has turned from a dominant population into an endangered population. Based on the former and present studies on Dovetree, some protection strategies were put foreword for protecting this ancient and rare species. Keywords Davidia involucrate - Dovetree - Geographical Distribution - Biological Characteristics - Protection Policy CLC number S718.4 Document code A Article ID 1007-662X(2004)01-0039-06 Foundation Item: This research was coordinated by the National Natural Science Foundation of China (No. 39970591)Biography: Wu Gang (1965-), Male, Professor in Key Laboratory of Systems Ecology, Research Center for Eco Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.Responsible editor: Chai Ruihai

一种改进的珙桐(Davidia involucrata)干种子总RNA的提取方法

After many unsuccessful attempts to obtain biologically active mRNAs from dry seeds of Davidia involucrata using available protocols,an effective procedure modified from Vicient and Delseny (1999) is developed.This method is based on the use of 8mol/L LiCl in the extraction buffer followed by phenol extractions.The differences with respect to the original method are the inclusions of 2% soluble PVP (10000Da) and 10 mmol/L cysteine in the extraction buffer to avoid oxidation of polyphenolics,the reduction in the number of phenol extractions,freezing the seeds for 10 minutes instead of using quarts.The author modifications conquer the perishing oxidation of polyphenolics,in their oxidized forms,polyphenols can covalently bind to proteins and nucleic acids; and permit the recovery of and an average of 240 μg total RNA per g of the seeds that is suitable for translation in vitro,northern hybridizations,and the construction of cDNA libraries.

一种改进的珙桐(Davidia Involucrata)干种子总RNA提取方法(英文)

改进后的方法在提取缓冲液中加入了2%的PVP(分子量10000)和10mM的半胱氨酸以避免多酚类物质的氧化,减少了苯酚抽提的次数.使用该改进的方法可以从平均每克珙桐干种子中获得240μg的总RNA,这些总RNA适合用于体外反转录、Northern杂交以及cDNA文库的构建.

A Preliminary Vegetation-Ecological Study of <i>Davidia involucrata</i>Forest

Davidia involucrata is a rare endangered species belonging to the paleo-tropical flora of the Tertiary period, endemic to China, and has an important protection and ornamental value. However, the natural populations and distribution areas of this ancient plant have been decreased sharply, because it suffers much disturbance from human activity in many regions. In this paper, data on Davidia involucrata forest in its most natural distribution areas were collected;the percentages of geographical areal types of seed-plant genera (Sensu Wu 1991) were summed;the community types were summarized using Braun-Blanquet methodology;and the geographical differentiation among communities was analyzed by detrended canonical correspondence analysis. The analysis of geographical types shows that temperate species are dominant and that tropical species also make up a high percentage. This indicates that Davidia involucrata forest is mainly temperate vegetation. In total, 16 communities were recognized by classification, and these communities were usually dominated by deciduous broad-leaved species, sometimes mixed with some evergreen species. The shrub layer of Davidia involucrata forest is generally occupied by bamboos. The geographical patterns among the communities are influenced mainly by temperature and moisture availability, and the forest is most likely to grow in warm, humid habitats.

Effects of life-history components on population dynamics of the rare endangered plant <i>Davidia involucrata</i>

In order to estimate the most effect stage and process on population growth and effective conserve the rare endangered plant Davidia involucrata, we analyzed the dynamics and the contributions of life-history components on population dynamics based on Lefkovitch matrix model and sensitivity analysis. The life cycle of Davidia involucrata was divided into six stages (seed, seedling, juvenile, immature, early adult and late adult) based on the species characteristics and published literature data, the survival rates in each life-history stage were simulated using a static life table, and the fecundity of each stage was determined according to sample information. The results showed that the structure of the observed population was not ideal, and the numbers of seedlings and coppice shoots was similar. The population growth rate was influenced largely by individual growth process, and asexual reproduction made a larger contribution to population growth than sexual reproduction. However, sexual reproduction was more important than asexual reproduction, because most asexual reproducing individuals (the coppice shoots) were derived mainly from human destruction (e.g. felling trees). The most important stage was stage V (late adult), associated with seed production and germination. Therefore, conservation of Davidia involucrata populations should focus on stage V and sexual reproduction, in order to improve the seed production and germination rate, and to promote population stability and development.

Isolation and Identification of an Endophytic Strain with Antibiosis Ability from Davidia involucrate Brail.

[Objective]The aim was to isolate and identify an endophytic bacteria strain with antimicrobial activity from Davidia involucrate Brail.[Method]Endophytic strain with antibiosis ability was isolated from D.involucrate Brail by using cylinder-plate method.Then,it was identified through physiological and biochemical tests,16S rDNA homology analysis as well as some gene-specific sequence analysis.[Result]B221 stain had antimicrobial activity against a variety of rice plant pathogens,and it was identified as Bacillus subtilis.[Conclusion]This study enriches the research on endophyte within D.involucrate Brail,application of Bacillus bio-control,and therefore has laid a good foundation for the development of fungus used in biological control of crop pathogens.

珙桐(Davidia involucrata Baill)研究综述

珙桐(Davidia involucrata Baill)作为第三纪古热带孑遗树种,国家一级保护植物,具有特殊的科学研究价值和极高的观赏价值。20世纪80年代以来受到了有关方面及科研工作者的广泛重视。从以下4个方面对珙桐研究现状进行了综述:(1)解剖学与生物学特征及珙桐在系统发育中的归属问题研究;(2)生态学特性与珙桐自然分布区生态条件的研究;(3)珙桐的种群生态学与群落生态学研究;(4)珙桐的繁殖与人工引种研究。

珙桐Davidia involucrata Bail.

落叶乔木,高15～20m;树皮灰褐色,不规则片状剥落。芽鳞覆瓦状排列。叶宽卵形,长9～15cm,宽2.5～4.5cm,基部心形,先端渐尖,叶边缘具明显锯齿;叶面近无毛。

云南乌蒙山国家级自然保护区珙桐林生态化学计量特征

【目的】探究国家Ⅰ级珍稀濒危植物珙桐生态化学计量特征,揭示珙桐林生态系统养分元素状况和生长限制因子。【方法】在云南乌蒙山国家级自然保护区不同海拔段设置4个样地,编号分别为Ⅰ、Ⅱ、Ⅲ、Ⅳ,利用单因素方差分析及多重比较等方法研究珙桐林叶片-凋落物-土壤3种组分C、N、P含量及其比值的差异性、相关性,用冗余分析方法探究土壤化学计量特征的响应因子。【结果】珙桐叶片C、N、P平均含量分别为520.97、22.73、1.43 g/kg,凋落物C、N、P平均含量分别为459.87、10.96、1.35 g/kg,土壤C、N、P平均含量分别为74.81、7.94、0.79 g/kg,叶片、凋落物、土壤C、N、P平均含量表现为叶片>凋落物>土壤。不同样地同一组分间土壤C、N、P含量差异显著,表现为Ⅳ>Ⅲ>Ⅱ>Ⅰ(Ⅰ:58.47±1.88、5.73±0.41、0.06±0.02 g/kg;Ⅱ:64.45±2.29、6.82±0.19、0.61±0.08 g/kg;Ⅲ:75.94±1.32、7.88±0.16、1.11±0.06 g/kg;Ⅳ:100.39±1.24、11.32±0.25、1.36±0.10 g/kg),叶片、凋落物差异不显著;同一样地不同组分间C含量差异显著,表现为叶片>凋落物>土壤,N、P含量差异不显著;不同样地同一组分、同一样地不同组分间C∶N、C∶P、N∶P存在显著差异。叶片、凋落物、土壤C、N、P含量及比值间相关性显著;海拔、非毛管孔隙度和坡度、毛管孔隙度、粉砂粒含量是影响土壤养分含量的关键环境因子。【结论】云南乌蒙山国家级自然保护区珙桐林不同海拔样地间土壤C、N、P含量及其比值存在显著差异,叶片、凋落物差异不明显,根据生态化学计量特征表明样地Ⅳ珙桐生长受P元素限制,海拔、非毛管孔隙度、坡度、毛管孔隙度、粉砂粒含量是影响珙桐林土壤养分循环的关键环境因子。

珙桐叶绿体基因组同义密码子使用偏好性分析

【目的】珙桐是蓝果树科珙桐属唯一现存的第三纪孑遗植物,是我国一级保护的特有濒危树种。分析其叶绿体基因组同义密码子使用偏好性及其主要影响因素,旨在为珙桐分子水平上的深入研究、物种保护和种质创新提供参考。【方法】从NCBI在线数据库下载完整的珙桐叶绿体基因组序列,并进行蛋白编码序列筛选,再利用CodonW软件计算各基因的有效密码子数(ENC)、密码子适应指数(CAI)、同义密码子相对使用度(RSCU)和密码子中A、T、C、G这4种碱基的含量,最后利用R软件计算各参数间的相关性并绘图。【结果】(1)从珙桐叶绿体基因组中共筛选出59条蛋白编码序列,总的鸟嘌呤和胞嘧啶碱基(GC)平均含量和密码子第3位碱基的GC平均含量分别为38.05%和30.63%,CAI平均值为0.18,ENC平均值为48.52,表明珙桐叶绿体基因组基因表达水平较低,且密码子使用偏好性较弱。(2)ENC-plot、PR2-plot、中性绘图和对应性分析表明,影响珙桐叶绿体基因组同义密码子使用偏好性的最主要因素为选择压力。(3)共筛选出12个最优密码子。【结论】珙桐叶绿体基因组同义密码子使用偏好性较弱,除了主要受选择压力影响外,还受到突变压力、碱基组成和基因表达水平等因素的影响;同时筛选出12个最优密码子,可用于未来珙桐的遗传改良和种质创新研究之中。

国家重点保护植物珙桐叶片功能性状地理格局及其驱动因素

以国家重点保护植物珙桐(Davidia involucrata Baillon)为研究对象,对其分布区内18个种群的17项叶片功能性状进行测量,探究叶功能性状的地理格局与对异质环境的适应机制。结果显示,在局域尺度上,珙桐叶片功能性状变异系数介于1.48%~24.81%,其中,叶碳磷比变异程度最大,叶有机质含量变异最小。随着经度或纬度的增加,珙桐叶片叶锯齿数、叶面积、叶厚度显著降低。随着海拔的增加,珙桐叶片叶磷含量、叶面积、叶厚度、叶干物质含量显著增加,珙桐叶片形状变得更宽且更近于圆形。叶片边缘锯齿增强了珙桐叶片对于寒冷的适应性。环境因子解释了79.90%的珙桐叶片性状变异,该变异主要由地理变量与气候因子驱动,同时受到土壤因子的影响。年降水和土壤氮元素是叶片性状变异的最强解释因子,随着降水增加或者土壤氮元素减少,叶片变得小且薄。研究结果说明,珙桐叶片功能性状在物种分布区尺度上呈现出明显的地理格局,其中降水、土壤氮元素含量在地理格局的形成中发挥了重要的作用。

珙桐(Davidia involucrata Baill.)苞片功能性状及性状间关系对海拔的响应

珙桐(Davidia involucrata Baill.)的苞片被认为是对传粉者和非生物因素等驱动力的适应,往往受到环境因子的影响。为揭示其功能性状及其性状间关系对海拔的响应,本研究采用独立样本t检验和标准化主轴分析方法对比了四川龙苍沟1400和1800 m不同海拔珙桐种群中花苞片的功能性状和性状间关系。结果显示:1)低海拔(1400 m)珙桐种群大、小苞片的长、宽和面积,以及单花苞片总面积均显著大于高海拔(1800 m)种群(P<0.05),且高、低海拔种群的大、小苞片面积及重量呈等比例生长;2)低海拔珙桐种群大、小苞片干重及单花苞片总干重均显著高于高海拔种群(P<0.05);3)高、低海拔种群的花序轴长与干重均无显著差异(P=0.446;P=0.791),高海拔花序轴干重与长间呈异速生长关系,而低海拔呈等速生长关系;4)珙桐大、小苞片的长宽间、面积间以及重量间关系在高、低海拔上均表现出等速生长,单花苞片的总面积和总干重分别与花序轴干重在高、低海拔上均表现出等速生长关系,而与花序轴长表现出异速生长关系。上述结果表明,珙桐苞片的功能性状及其性状间关系在不同海拔存在显著差异,这种现象可能是其在长期进化过程中抵抗环境干扰、保护繁育器官和提高授粉几率而形成的一种适应策略。

珙桐体细胞胚胎发生技术研究

研究探讨基本培养基类型对珙桐愈伤组织诱导的影响、植物生长调节剂对胚性愈伤组织诱导及体胚发育的影响,初步建立以未成熟合子胚为外植体,通过体细胞胚胎发生途径再生珙桐植株的培养方案。结果表明,在含有3%蔗糖、0.3%凝胶、800 mg/L水解酪蛋白、400 mg/L L-谷氨酰胺的MS、1/2MS和WPM基本培养基上均可诱导出愈伤组织,以MS+2.0 mg/L 2,4-D+0.5 mg/L 6-BA诱导率最高,可达94.0%;胚性愈伤组织在MS+0.5 mg/L NAA+1.0 mg/L 6-BA的培养基上诱导效果较好;在MS+0.5 mg/L NAA+1.0 mg/L 6-BA培养基上,体胚诱导率可达22.9%;成熟体胚在1/2MS+0.5 mg/L 6-BA+0.25 mg/L IBA的萌发培养基上能正常萌发,其后在添加1 g/L活性炭的萌发培养基上转化成完整小植株。组织细胞学观察表明,珙桐体胚起源于胚性愈伤组织,经历了球形期、心形期、鱼雷期和子叶期发育阶段,这与自然条件下的合子胚形成过程相似。

烟台地区珙桐种子育苗研究初探

本研究通过对引种烟台多年生珙桐结实种子进行催芽、育苗、遮荫试验,与原产地直接引种的一年、两年种子进行试验对比,分析迁地保护多年后珙桐繁殖体在烟台的适应性,以期为迁地保护提供技术支撑。结果显示,引种烟台珙桐多年后的结实种子经过两年催芽处理,在萌芽初期具有较高的出芽率和成活率,平均新生株数量最高,种子繁殖系数最高,苗高、地径在温室阶段生长慢,但在大田条件下,生长较快,高于同期直接引种四川种子。此外,试验得出,林缘处理下的种苗质量要优于全遮荫下种苗质量,一年生种子虽苗高、地径高于两年种子,但木质化程度较差、种子繁殖系数低。

两年生珙桐幼苗在北方沿海地区迁地栽培试验研究

该文旨在分析2 a生珙桐幼苗在北方沿海地区的栽培适应生长规律,为迁地保护提供技术支撑。在烟台沿海地区3种不同立地条件下,进行珙桐幼苗迁地保护栽培试验,分析其生长指标,并对越夏、越冬问题进行技术探究。结果显示:2 a生珙桐幼苗在无防护情况下,野外栽培成活率较低,栽培2 a后,保存率在29.0%~45.0%之间。夏季出现枯梢现象,叶片受损严重,含水量偏低,同时根部萌生新植株。栽培试验对比得出,珙桐幼苗无防护情况下,更适合生长在低山区,其次为丘陵区、平原区。夏季半遮阴、地表铺盖无纺布措施能显著提高成活率,提升苗木质量,减少灼伤。冬季树干包被无纺布和薄膜,能够显著提高越冬成活率,减少枯梢率,促进早春萌芽,提高叶片质量。

武陵源风景名胜区珙桐群落主要树种特征光谱研究

为探明湖南省张家界市武陵源风景名胜区珍稀植物珙桐(Davidia involucrata Baill.)及其群落主要树种的特征光谱,借助ASD FieldSpec 4型便携地物光谱仪,运用微分法和去包络线法分析了珙桐、野鸦椿[Euscaphis japonica(Thunb.)Dippel]、红枫(Acer palmatum‘Atropurpureum’)、香樟[Cinnamomum camphora(Linn)Presl]、木荷(Schima superba Gardn.et Champ.)5类树种的反射光谱。结果表明,原始光谱曲线位于近红外波段处,珙桐群落主要树种反射率差异明显,可用于识别的最优波段为780~920 nm、1000~1349 nm、1427~1590 nm、1590~1785 nm、1981~2459 nm;490~530 nm、550~582 nm、680~760 nm、1110~1190 nm是一阶微分数据结合“三边”参数分析得出的最佳区分波段;基于去包络线曲线分析,曲线突出显示的4个吸收谷和1个反射峰,其特征波段是440~500 nm、520~640 nm、640~690 nm。光谱吸收特征参数基于曲线去包络线540~760 nm波段数据分析得出,可以通过该波段的吸收峰面积和光谱吸收系数对该5类树种进行区分。

卧龙自然保护区珙桐林下资源调查初报

为了解卧龙自然保护区珙桐林下乔木、灌木和草本的资源情况,2021年2月至11月,采用设置样方的形式进行珙桐调查,综合参考文献,本次调查发现珙桐林中乔木层物种48种、灌木层物种34种和草本层物种56种,研究其种类及隶属科、属,分析珙桐天然林与日本落叶松人工林林下群落生态、优势属种间的差异,以期为保护野生珙桐资源提供基础信息和科学依据。

外源水杨酸对盐胁迫下珙桐幼苗抗氧化系统和基因表达的影响

通过对珙桐(Davidia involucrata)幼苗进行水杨酸(SA)处理,探讨在盐胁迫下SA对珙桐叶片膜脂过氧化程度、活性氧(ROS)积累、抗氧化酶活性、抗氧化剂含量等生理指标及基因表达的影响。结果表明:施用2 mmol·L^(-1)的SA可以显著降低盐胁迫下珙桐幼苗的相对电导率,抑制丙二醛(MDA)和ROS的积累,提高相对含水量、抗氧化酶(SOD、POD和APX)活性以及谷胱甘肽(GSH)含量。施用SA导致盐胁迫下2581个珙桐基因表达发生变化,其中1516个上调表达,1065个下调表达。KEGG分析发现,差异表达基因富集在包括苯丙烷类生物合成在内的9条通路。此外,转录组与实时荧光定量PCR结果均显示,在盐胁迫条件下,转录因子基因DiWRKY40、DiNAC25、DiMYB4和DiMYB86的表达受到SA的显著诱导。研究表明,外源SA可在盐胁迫下刺激珙桐幼苗产生逆境应答,引起基因表达发生变化,进而缓解盐胁迫对珙桐幼苗的伤害。

梵净山自然保护区珙桐萌蘖繁殖在种群数量中的作用

为探讨梵净山自然保护区珙桐(Davidia involucrata)的繁殖策略,揭示萌蘖苗和实生苗在维持种群数量中的作用。采用每木调查法调查贵州省梵净山自然保护区标水岩珙桐种群,根据调查数据绘制径级结构图。以珙桐径级结构代替年龄结构,采用匀滑技术分别编制了萌蘖苗和实生苗种群静态生命表,并绘制存活曲线、死亡率曲线、消失率曲线及4个生存函数曲线。结果显示:(1)珙桐种群年龄结构存在一定的波动性,按萌蘖苗统计则幼龄个体占78.78%,按实生苗统计则幼龄个体占21.45%,两种统计的珙桐种群的生存曲线接近于DeeveyⅡ型。(2)珙桐种群整体是增长的,萌蘖苗V_(spi)高于V_(sepi)(6.50%>2.30%)。(3)珙桐种群生存率呈单调下降趋势,萌蘖苗较明显。(4)珙桐种群累计死亡率呈单调上升的趋势,萌蘖苗更明显。(5)珙桐种群生存率和消失率曲线呈单调上升趋势,萌蘖苗和实生苗基本一致。标水岩珙桐种群属于增长型种群,存活曲线为DeeveyⅡ型,后期种群保持稳定,萌蘖繁殖有利于维持种群数量,在维持种群稳定中具有十分重要的作用。