Low genetic diversity in the endangered marine alga Silvetia siliquosa(Ochrophyta:Fucaceae)and the implication to conservation

Although signifi cant research eff orts have been targeted toward conservation and management of endangered terrestrial fl ora and fauna,attempts have been limited to conserve threatened seaweeds.Silvetia siliquosa is an ecologically and commercially vital brown alga that is uniquely distributed in the Yellow-Bohai Sea and along the southwest coast of Korea.A massive decline in its distribution range and biomass from the mid-1990s onward indicates that this species has become endangered.In the present study,we used nuclear internal transcribed spacer and concatenated mitochondrial cytochrome oxidase I subunit+intergenic spacer to estimate the genetic diversity,population connectivity,and degree of genetic diff erentiation of S.siliquosa in China and Korea.The molecular results exhibited strikingly low levels of haplotype/ribotype and nucleotide diversity in S.siliquosa populations,with only three mitochondrial haplotypes and nuclear ribotypes detected in 136 and 143 specimens,respectively.The analysis of molecular variance revealed 85%-95%of genetic variance among populations.Population diff erentiation coeffi cient(F_(ST))and gene fl ow(N_(m))suggested that two populations(JIN and GWA)along the southern coast of Korea are highly divergent from the others,with weak genetic exchange.No signifi cant genetic diff erentiation was observed among populations either in China or along the geographically proximate west coast of Korea.Thus,four independent management units were designated for sustainable management:the LII and RUS populations in China,the YEO and CHA populations along the west coast of Korea,and each of the GWA and JIN populations along the south coast of Korea.We suggest that artifi cial cultivation and transplantation of S.siliquosa are the eff ective approaches for restoration and conservation.

Mating system and genetic diversity of a rare desert legume Ammopiptanthus nanus (Leguminosae)

Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP diversity in A. nanus populations and investigated the mating system of this species using progeny arrays assayed for polymorphic allozyme loci. Mating system analysis in the Keyi＇eryongke＇er population showed low levels of outcrossing, and strong inbreeding depression. Low levels of genetic variation were detected at both population （allozyme, Pp=14.0%, A=l.14, He=0.031; AFLP, Pp=14.5%, Shannon＇s information index I=0.063） and species （allozyme, Pp=21.1%, A=1.21, He=0.040; AFLP, Pp=20.9%, I=0.083） levels; while moderate genetic differentiation existed among populations, as indicated by allozymes （Gsa-=0.081） and AFLP （GST=0.151-0.193）. Founder effect, bottlenecks in evolutionary history, the mixed mating system and co-ancestry may have influenced the level of genetic diversity in A. nanus. Markers of both types provide new insights for conservation management, indicating that the Biao＇ertuokuoyi and Keyi＇eryongke＇er populations should be given priority for in situ conservation and regarded as seed sources for ex situ conservation.

RAPD Analysis for Genetic Variation within the Endangered Quillwort Isoetes hypsophila (Isoetaceae)

The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 104 DNA fragments were scored, of which, 52 were polymorphic loci. Low-level genetic diversity within populations with PPB values ranging from 7.69%to 25.96%was found. An Anal ysis of Molecular Variance (AMOVA) indicated that the most of variance (78.30%) occurred between Yunnan and Si chuan. The variances among populations within regions and within populations were only 3.89%and 17.82%, respectively.

无柄醉鱼草与大叶醉鱼草的遗传多样性解析

无柄醉鱼草(Buddleja sessilifolia)是狭域分布的极小种群野生植物(Plant Species with Extremely Small Populations,PSESP),大叶醉鱼草(B.davidii)则是广布种,二者亲缘关系较近,且同为四倍体。通过比较濒危物种与近缘广布种的遗传多样性,可以了解濒危物种的演化历史,为制定保护策略提供理论依据。本研究通过简单重复序列(Simple Sequence Repeats,SSR)分子标记对无柄醉鱼草5个居群(126个个体)和大叶醉鱼草14个居群(206个个体)进行遗传多样性和遗传结构解析,并提出对无柄醉鱼草的保护建议。结果表明,无柄醉鱼草和大叶醉鱼草各居群的期望杂合度(He)平均值分别为0.606、0.775,Shannon′s多样性指数(I)平均值分别为1.162、1.729,两个物种均具有较高的遗传多样性,但广布种大叶醉鱼草遗传多样性水平高于狭域种无柄醉鱼草;无柄醉鱼草和大叶醉鱼草遗传分化系数(F ST)分别为0.043和0.024,两个物种居群间遗传分化程度均较低。遗传结构分析结果表明,无柄醉鱼草5个居群可划分为2个集群,居群间地理距离与遗传距离不存在相关性;大叶醉鱼草14个居群可划分为3个集群,居群间地理距离与遗传距离相关。结合野外居群现状,建议对无柄醉鱼草划分保护单元,重点对丹珠居群和独龙江隧道口居群开展就地保护,同时采取种质资源收集、人工繁育等保护措施。

珍稀濒危植物阜康阿魏的遗传多样性及遗传结构

明确珍稀濒危小种群阜康阿魏(Ferula fukanensis)的遗传多样性和遗传结构,是对其制定有效的保护和管理策略的基础和前提。本研究基于10对多态性好且可以稳定扩增的SSR引物对来源于3个居群87个珍稀濒危植物阜康阿魏的遗传多样性和遗传结构进行分析。结果显示:小种群的阜康阿魏具有相对较高的遗传多样性,居群间Nei’s基因多样性指数(h_(S))为0.514,总的Nei’s基因多样性指数(h_(T))为0.516,观测杂合度(H_(o))为0.881,期望杂合度(H_(e))为0.512,香农信息指数(I)为0.836,多态位点百分率(P_(PB))为100%,遗传分化程度较低(F_(st)=0.007),95.9%的变异发生在居群内,遗传距离与地理距离无显著相关性,66.7%的居群遭遇了遗传瓶颈。结果表明,阜康阿魏遗传变异丰富,有较高的进化潜力。结合该种野外种群现状,建议建立保护区,开展就地保护,并加强引种和人工繁育等迁地保护措施,辅助阜康阿魏保育。本研究可为阜康阿魏植物资源保护提供理论支持,具有重要的理论和实践意义。

The whole-genome survey of Acer griseum,its polymorphic simple sequence repeats development and application

Background:Acer griseum Pax is an endangered species endemic to China with both ornamental and economic value.However,the lack of information on its genome size and characteristics hinders further work at the genome level.Methods:This paper applied bioinformatics methods to predict the characteristics and patterns of the A.griseum genome,providing an important basis for formulating its whole-genome sequencing scheme.This study also characterized the simple sequence repeats(SSRs)of A.griseum,laying the foundation for the development and application of genome-wide SSR markers.In this study,PE150 sequencing was performed by the BGI MGISEQ platform,and the sequence files were analyzed by the K-mer method to estimate the characteristic information by GCE software.Results:The genome size was finally determined to be 739.63 Mb,its heterozygosity ratio was 1.33%,and the repetition ratio was 65.68%.A total of 825,960 SSR loci were identified in the assembled genome sequence,and primers were successfully designed for 526,020 loci.To verify the effectiveness of these primers,100 pairs of primers were randomly selected and synthesized,and 81 pairs successfully amplified the target fragments.Fourteen pairs of primers with good polymorphism were selected for principal component analysis of 31 A.griseum individuals from two populations,showing favorable heterozygosity and PIC values.According to the findings,these SSRs might identify genetic variations based on geographic areas.Conclusion:It is suggested that Illumina+PacBio assembly strategy should be used for whole-genome sequencing due to the high heterozygosity rate and high repetition rate of the genome.In addition,the SSR primers designed in batches in this study laid a foundation for the in-depth study of population structure and population maintenance mechanism of A.griseum,which is helpful for the effective conservation and sustainable utilization of this germplasm resource.

Population Genetic Structure of the Medicinal Plant Vitex rotundifolia in China: Implications for its Use and Conservation

Vitex rotundifolia L. is an important plant species used in traditional Chinese medicine. For its efficient use and conservation, genetic diversity and clonal variation of V. rotundifolia populations in China were investigated using inter-simple sequence repeat markers. Fourteen natural populations were included to estimate genetic diversity, and a large population with 135 individuals was used to analyze clonal variation and fine-scale spatial genetic structure. The overall genetic diversity （GD） of V. rotundifolia populations in China was moderate （GD=0.190）, with about 40% within-population variation. Across all populations surveyed, the average within-population diversity was moderate （P = 22.6%; GD = 0.086）. A relatively high genetic differentiation （Gst = 0.587） among populations was detected based on the analysis of molecular variance data. Such characteristics of V. rotundifofia are likely attributed to its sexual/asexual reproduction and limited gene flow. The genotypic diversity （D = 0.992） was greater than the average values of a clonal plant, indicating its significant reproduction through seedlings. Spatial autocorrelation analysis showed a clear within-population structure with gene clusters of approximately 20 m. Genetic diversity patterns of V. rotundifolia in China provide a useful guide for its efficient use and conservation by selecting particular populations displaying greater variation that may contain required medicinal compounds, and by sampling individuals in a population at 〉20 m spatial intervals to avoid collecting individuals with identical or similar genotypes.

珍稀濒危药用植物黄檗野生种群遗传多样性的AFLP分析

黄檗(Phellodendronamurense)是我国珍贵的药用和用材树种,现已被列为国家二级保护植物。为了研究其遗传多样性和遗传结构,以制定有针对性的保护策略,作者采用8对荧光引物,对来自10个野生种群共计129个黄檗个体进行了AFLP分析。共扩增出1,704条谱带,其中多态带1,581条。遗传分化系数Gst为0.3420,即有34.20%的遗传变异来自种群间。黄檗物种水平的遗传多样性高于种群水平:在物种水平上,多态位点百分率PPL=92.77%,有效等位基因数Ne=1.4636,Nei’s基因多样性指数H=0.2316,Shannon信息指数I=0.4275;在种群水平上,PPL=54.20%,Ne=1.2487,H=0.1524,I=0.2371。UPGMA聚类结果表明,黄檗野生种群可分为四类,并且来自同一地区的黄檗个体有聚为一类的趋势,说明其遗传变异可能与生境有关。建议在各种群内大量采样,实施迁地保护;在长白山、完达山、大兴安岭、小兴安岭、千山以及燕山山脉的云蒙山等地区,均匀布点划分区域进行就地保护,保护种群完整性,促进种群自我更新。

中华水韭遗传多样性的RAPD分析

采用 RAPD方法对珍稀濒危植物中华水韭(Isoetes sinensis)4个自然居群的48个样品进行了DNA多态性分析。从60个随机引物中筛选出14个有效引物,共产生124条DNA片段,其中72条为多态性条带,总的多态位点百分率(PPB)为58.06％。各居群间多态位点百分率差异显著(0.81％-12.90％)。AMOVA分析结果表明,4个居群间基因分化系数Φ_(st)=0.5894,即遗传变异中有相当一部分来源于群体间(58.94％)。日益缩小的种群规模而导致的居群内近交和遗传漂变的发生以及居群间有限的基因交流可能是中华水韭目前遗传结构的主要成因。鉴于目前中华水韭居群内个体数偏少、遗传多样性较低的现状,建议对其进行就地保护并保护尽可能多的生境,对不同自然居群内的个体进行植株相互移栽和育苗移栽,以提高不同居群间的基因交流,尽可能地保护中华水韭的遗传多样性。

云南古茶树(园)遗传多样性的ISSR分析

云南省保存有20多万亩古茶园，这些古茶树（阿萨姆变种Camellia sinensis vat．assamica）种质资源可能含有各种优良基因，对未来茶树良种选育有重要意义。本研究采用ISSR分子标记技术对云南省十个有代表性的古茶园遗传多样性进行分析，十个居群的多态位点百分率（P）为56．5％-90．9％；Nei’氏遗传距离（He）居群平均是0．281，阿萨姆变种水平内是0．461；Shannon多样性指数（HD）居群平均是0．418，阿萨姆变种水平内是0．653。而居群间遗传分化系数Gst=0.391，和Shannon多样性指数分析（36．0％）和AMOVA分析结果（39．7％）相一致，说明阿萨姆变种60．9％的遗传变异来自居群内的个体间，39．1％的遗传变异来自居群间。研究结果揭示阿萨姆变种居群遗传多样性高，居群间遗传变异存在中度的遗传分化，这可能是由于茶树种内高度异的特性和生境片段化所致。基于观察到的居群遗传信息，建议采取就地保护和迁地保护的保护策略。

孑遗植物杜仲的遗传多样性RAPD分析和保护策略研究

目的:进行杜仲群体遗传多样性的研究。方法:采用随机扩增多态DNA(RAPD)方法对杜仲的16个群体、260个个体进行遗传多样性分析。结果:用10个随机引物共扩出110条清晰条带,其中多态性条带为106条,总的多态位点百分率为96.36,平均多态位点百分率为38.92。Ne’is基因多样性指数H=0.246 1,Shannon’s多态性信息指数I=0.386 8。基因分化系数Gst=0.424 4。结论:杜仲种内具有丰富的遗传多样性,而不同群体内部的遗传多样性低。遗传分化分析表明杜仲群体间已发生了高度的遗传分化,因此,生物多样性保护时应尽可能保护更多的种群。

RAPD标记在植物系统进化研究中的应用

介绍了RAPD原理，对DNA谱带的数据分析作了较详尽的阐述，列举了几种常用于RAPD产物分析的软件包，探讨了几年来RAPD在种质资源鉴定、遗传多样性分析、植物分类、物种的亲缘关系研究及其在物种起源和演化上的应用进展及其存在的缺陷，进一步展望了RAPD在濒危物种保护和研究中的应用前景．

海南海桑遗传多样性的ISSR研究

采用简单序列重复区间扩增(ISSR)分子标记技术对分布于海南岛的海南海桑Sonneratiahainanensis4个种群共33个个体进行了遗传变异分析。11条引物共扩增出166条带,其中142条具多态性,多态位点百分率为85 54%。在种群水平上多态位点百分率14 46%～80 12%,平均为46 24%。期望杂合度、Shannon信息指数在物种水平上分别为:0 2329和0 3619;在种群水平上分别为0 1538和0 2317。依据Gst值,海南海桑遗传变异发生在种群内的个体间占75 89%,24 11%的遗传变异发生在种群间。UPGMA聚类结果为来自文昌的2个天然种群聚为一类,东寨港引种栽培的2个人工种群聚为另一类。Mantel检验表明海南海桑种群间的遗传距离与地理距离间存在显著的正相关(P<0 05)。种群遗传多样性与环境因子间的相关性分析表明:海南海桑的遗传多样性水平与土壤总氮量、有机质含量呈显著负相关(P<0 05)。

孑遗植物水杉的遗传多样性研究

采用随机扩增多态DNA(RAPD)方法对孑遗植物水杉 (Metasequoiaglyptostroboides)的 8个居群 (包括 6个孑遗居群和 2个人工栽培居群 )的 48个个体进行了遗传多样性研究。用 16个随机引物共扩增出清晰谱带 5 7条。孑遗居群平均多态位点百分率为 38.6 %。各居群多态位点百分率差异显著 ( 10 .5 3%～ 33 .33 % ) :湖北利川的小河和桂花 2个居群较高 ,分别是 33 .33%和 31.5 8% ;湖南龙山洛塔居群较低 ,为 10 .5 3 %。人工栽培居群中 ,美国密西根州和湖北武汉 2个居群的多态位点百分率也较低 ,仅分别为 10 .5 3 %和 8.77%。用POPGENE 1.31版软件进行数据处理后结果如下 :孑遗居群的平均Nei’s基因多样性为 0 .130 5 ,Shannon’s遗传多样性信息指数为 0 .192 1,水杉孑遗居群遗传距离与地理距离的相关系数r =0 .2 346 6 (P =73 .2 7% ) ,基因分化系数Gst=0 .10 82 ,表明居群间有一定分化。用UPGMA方法聚类可知 ,2个人工居群与湖北利川居群优先聚类。鉴于目前水杉孑遗居群生境人为破坏严重、遗传多样性较低和原生母树分布分散 ,建议在湖北利川小河和桂花野生水杉最适生境建立水杉遗传多样性保护点 ,将现有的 2 5 0多株原生母树分别采种育苗定植于保护点 ,以达到最大限度地保存现有水杉遗传多样性的目的。

基于SNP分子标记的凹叶木兰遗传多样性初步研究

凹叶木兰是我国特有的木兰属植物,仅分布于我国四川和云南两省相邻地区,目前已被列入中国物种红皮书名录,属易危物种。该研究以采自四川南部麻咪泽和美姑大风顶两个自然保护区的野生凹叶木兰为材料,利用以PCR和测序为基础的SNP分子标记方法,初步研究了凹叶木兰的遗传多样性。结果表明:在扩增出的4条510bp长的序列上,平均在73bp左右的序列长度上能够检测到一个SNP位点,说明两个自然保护区内不同居群的凹叶木兰具有较高遗传多样性;序列间相似度达97%,与引物所对原序列相似度达36%,表明该序列适宜进行凹叶木兰遗传多样性研究。研究结果为进一步开展凹叶木兰遗传多样性的研究及其保护政策的制定提供了参考。

保护遗传学及其在濒危植物研究中的应用

保护遗传学是应用遗传学的原理和方法 ,主要研究生物多样性中的遗传多样性及其保护的新兴学科。文中介绍了保护遗传学的产生、研究内容和意义 ,及其在濒危植物保护中的应用。

云南松主分布区天然群体的遗传多样性及保护单元的构建

以20个云南松天然群体为对象,SSR分析表明云南松遗传变异主要存在于群体内,各群体间的遗传多样性水平差异不显著。基于SSR分子标记遗传多样性分析,根据Nei’s遗传相似度,采用逐步聚类优先取样法,分别对初始群体、遗传多样性保护单元和剩余群体进行比较、t检验,以此评价遗传多样性保护单元的代表性。结果表明,利用该方法抽样的群体能很好地代表初始群体的遗传多样性,按30%的群体抽样,等位基因数、有效等位基因数、Shannon’s信息指数和期望杂合度的保留率分别达到初始群体的98.03%、105.36%、103.99%和105.56%。保护单元的遗传多样性均高于剩余群体,抽样群体组成的遗传多样性保护单元的效果较好。

基于ISSR遗传多样性分析的云南蓝果树保护措施探索

保存种群的遗传多样性和进化潜力是成功拯救保护濒危物种的关键。云南蓝果树（Nyssa yunnanensis W.C.Yin）是国家I级重点保护的极度濒危野生植物,也是国家实施极小种群野生植物保护工程的目的物种。为了制定针对性的保护措施,采用ISSR分子标记方法对64株极度濒危物种云南蓝果树子代个体进行遗传多样性分析。从100条引物中筛选出12条ISSR引物,共扩增出77个稳定、清晰的条带。其中58个为多态性条带,物种水平上的多态性条带百分率（PPL）变动范围为50.00%-87.50%,平均值为（74.65±0.01）%;等位基因观察值（Na）为1.7532;有效等位基因观察值（Ne）为1.5804;Nei＇s基因多样性指数（He）为0.3206,多态性信息含量指数（PIC）变动范围为0.15-0.44,平均值为0.27±0.01;Shannon＇s遗传多样性信息指数（I）随着样本数的增加而升高,但当样本数达到24及以上时,Shannon＇s指数的数值基本不再变化。基于遗传多样性分析结果,从地质历史原因和人为干扰因素等方面对云南蓝果树的濒危机制进行了探析,并提出了有针对性的云南蓝果树保护措施。

中国6个国家级保护鸭种群遗传多样性分析(英文)

为探讨国家级保护鸭种群的遗传多样性和遗传分化关系,利用17个微卫星标记,对我国6个国家级保护鸭品种资源的遗传多样性进行了分析,统计了平均遗传杂合度(H)、多态信息含量(PIC)、基因多样度(FST)、平均遗传分化系数(GST)和遗传距离等。结果表明,各鸭品种的杂合度较高,除两个群体表现为显著的杂合子缺失外,其他群体均处于Hard-Weinberg平衡状态。6个鸭种群间平均FST值为17.0%,平均遗传分化系数GST为14.7%,各品种平均杂合度为0.706～0.604,平均多态信息含量(PIC)为0.561～0.663。本研究说明我国6个国家级保护鸭品种资源各品种内和品种间的遗传变异大,遗传多样性丰富。

植物保护遗传学

从遗传多样性、系统发育和地理系统发育角度对当前保护遗传学在植物保护中的作用进行了探讨。在植物保护过程中 ,要考虑种群遗传多样性的大小 ,在就地和迁地保护的过程要减少近交和远交衰退影响 ,并可利用遗传标记为提供关于种群大小、基因流动等方面的信息。系统发育和地理系统发育的研究在于了解物种进化的历史 ,以确定物种保护单元。同时结合两个具体生态学问题 (生境片断化和外来种 )对当前植物保护遗传学的研究进行了介绍 ,揭示了保护遗传学在植物保护上重要作用和不可取代性 ,为今后研究提供参考。