珍稀濒危蕨类植物东方水韭的遗传多样性

采用ISSR分子标记对珍稀濒危蕨类植物东方水韭和中华水韭4个自然居群共72个样品进行了DNA多态性分析。从65个随机引物中筛选出11个有效引物,共产生98条DNA片段,其中68条为多态性条带,多态位点百分率(PPL)为66.33%。东方水韭两个居群的多态位点百分比率(PPL)较低(8.16%和7.14%)。中华水韭两个居群的PPL也较低(9.18%和23.47%)。中华水韭物种水平上的PPL(51.02%)高于东方水韭(9.18%)。AMO-VA分析结果表明,东方水韭遗传变异中主要存在于居群内(94.74%),而中华水韭绝大部分的遗传变异却存在于居群间(86.71%)。东方水韭和中华水韭个体间UPGMA聚类结果表明:同一物种的个体完全能聚在一起,中华水韭的两个居群也能明显分开,而东方水韭两居群的个体并不能完全聚在一起。探讨了可能造成上述居群遗传结构模式的主要因素,同时提出今后工作中需重点解决的问题。     

极濒危植物中华水韭屯溪居群调查研究报告

中华水韭（Isoetes sinensisPalmer）为水韭科（Isoetaceae）水韭属（Isoetes）多年生沼泽植物,由于人为干扰日益严重,现分布范围急剧缩小,种群数量稀少,处于濒危状态,已被列为国家一级重点保护野生植物。为科学合理的保护和抢救这一珍稀濒危植物资源提供理论依据,为此对中华水韭屯溪居群的生长环境、面积、株丛数量、水体的pH值、伴生植物种类和生存现状等的调查研究。中华水韭屯溪居群面积500m^2,株丛密度较大,水体pH值为6.55,伴生植物有40余种,其中10种有较高优势度,生存面临多重威胁,保护迫在眉睫。     

极濒危植物中华水韭休宁居群的遗传结构

采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对极濒危蕨类植物中华水韭(Isoetes sinensis)现存于安徽休宁的5个亚居群的等位酶多样性和遗传结构进行了研究。结果表明：中华水韭居群每位点平均等位基因数A=1．7,平均多态位点比率P=55．56％,平均预期杂合度He=0．201。居群中半数的多念位点表现为等位基因的“固定杂合”,5个亚居群的遗传多样性无显著差异,但都表现出严重偏离Hardy—Weinberg平衡的杂合子过昔;其遗传变异主要发生于亚居群内(94．27％),亚居群之间的遗传分化较小(Gsl=0．0573),亚居群间遗传一致度较高(I=0．960—0．999)。我们推断这可能是由于居群构建之初的奠基者效应或者原种群曾经历了较为严重的遗传瓶颈所导致;此外亚居群间便利的基因交流也可能起到了很大作用(Nm=4．5062)。取自休宁居群的75株样品由13个专一多位点基因型(18个位点等位酶基因型)组成,亚居群及个体间高度遗传均质。本文还就中华水韭休宁野生居群濒危的遗传因素进行了探讨,并提出了相应的保育策略。     

低温胁迫对极度濒危植物中华水韭生理特性的影响

以人工繁殖的极度濒危级(CR)植物中华水韭(Isoetes sinensis Palmer)为试验材料,研究了0 ℃低温环境下胁迫0~20 d,沉水叶片中保护酶系统(POD、SOD、CAT)、渗透调节物质(可溶性糖和可溶性蛋白)、叶绿素以及丙二醛(MDA)和相对电导率的变化。结果显示:随着低温（0 ℃）胁迫时间的延长,中华水韭沉水叶片的相对电导率、可溶性糖含量、CAT活性先升高后下降,SOD活性呈逐渐上升的趋势,POD活性、可溶性蛋白含量、叶绿素含量下降,MDA含量一直低于CK,且在一定范围内波动。研究表明,中华水韭沉水叶片在0 ℃低温胁迫中受到一定程度的伤害,但能通过调节自身的膜透性、渗透调节物质含量和保护酶活性系统来减轻低温伤害,维持其正常生理代谢功能,从而表现出一定的抗寒潜力。     

基于AFLP分子标记技术的黑花韭与多星韭遗传多样性与亲缘关系分析

采用AFLP分子标记技术分析了分布在滇中、滇西、滇西北的3个黑花韭居群、3个二倍体多星韭居群和6个四倍体多星韭居群的遗传多样性与亲缘关系.结果表明,12个居群在DNA水平上已发生明显分化.居群间的基因分化系数(GST)为0.444.由GST计算的居群间基因流(Nm)为0.625,表明居群间部分基因流动受阻.12个居群间...     

中国特产2种濒危水韭雄性发育的比较研究

采用透射电镜和光镜比较观察了中华水韭和云贵水韭雄配子体及其精子的发育特征。结果显示:(1)2种水韭的雄配子体的寿命只有15~30d,终生都在小孢子壁内发育。(2)雄配子体只含有1个原叶体细胞、1个精子器壁细胞和4个精细胞,前2个细胞内含有丰富的营养物质。(3)精子由精核、微管带、鞭毛、细胞质等4部分构成。(4)中华水韭雄配子体发生率为4.5%,平均每个雄配子体产生0.46个精子,精子游动速度约53μm/s,寿命8min;云贵水韭雄配子体发生率和产精量略高于中华水韭,但精子游动速度和寿命略低于中华水韭。研究认为,中国水韭濒危的主要原因之一是雄配子体产精率低、受到生殖生态限制、水污染对精子的危害等;雄性特征表明水韭在石松类中占有较高的进化地位;结合前人的研究成果绘出了水韭雄配子体的发育模式。     

珍稀濒危蕨类植物中华水韭染色体数目的研究

蕨类植物中华水韭 Isoetes sinensis Palmer,隶属于拟蕨类水韭亚门水韭目水韭科水韭属。该亚门现仅存单目单科 2属 [1] ,形态特征独特 ,系统位置也原始而孤立 [2 ] ,其染色体资料对探讨单目单科水韭属植物的系统演化进而对蕨类植物系统演化均极具意义。水韭属植物全世界现存约 1 30种[1] ,主要分布于北半球 ,我国仅有 4种 ,且数量十分稀少 ,全部被列为国家一级重点保护对象 ,其中 ,中华水韭是中国境内发现的第一种水韭 ,现仅零星存在于江苏、安徽、浙江、江西的少数湿地 [3 ,4] ,已处于极度濒危状态 [4] 。目前有关水韭属植物染色体资料均…     

珍稀濒危植物安徽羽叶报春遗传多样性的RAPD分析

利用RAPD分子标记对安徽特有濒危物种安徽羽叶报春（Primula merrilliana）6个自然居群的134个个体的遗传多样性进行了研究。从100个随机引物中筛选出12个RAPD引物,扩增共得到158条带,其中129个多态性位点（PPL）。POPGENE分析显示安徽羽叶报春具有较丰富的遗传变异（PPL=81.65%,He=0.2515,Ho=0.3849）。Nei′s基因多样性指数计算的居群间遗传分化系数（GST=0.5511）与Shannon信息指数（54.48%）基本一致。生境的片段化和基因流障碍可能是导致居群间遗传分化显著的主要原因。针对安徽羽叶报春的居群遗传变异提出了相应的保护措施：保护好自然生境和现有的居群及个体;加强居群间的基因流动;在迁地保护过程中,在尽可能多的居群中采样,以提高栽培居群的遗传多样性。     

珍稀濒危植物太行菊遗传多样性的ISSR分析

利用ISSR分子标记技术对太行山特有濒危物种太行菊11个自然居群的遗传多样性进行研究。用10个引物对11个居群的122个样品进行扩增,共得到150个扩增位点,其中多态性位点149个,多态位点百分率(PPL)为99.33%。POPGENE分析显示,太行菊具有较高的遗传多样性(H=0.2149,I=0.3455)。沁阳市大西天居群的遗传多样性水平最高(H=0.1910,I=0.2969),山西陵川县大双村居群的遗传多样性水平最低(H=0.1356,I=0.2155)。Nei’s遗传多样性分析表明,11个自然居群间出现了较高的遗传分化(基因分化系数Gst=0.2566,基因流Nm=1.4488)。生境的的片段化和基因流障碍可能是导致太行菊居群间遗传分化显著的主要原因。通过对太行菊居群遗传多样性和遗传结构的分析,该文提出了一些保护策略。     

中华水韭

对我国野生一级珍稀濒危的孑遗植物中华水韭的形态特征、生境与生态分布、繁殖以及生活史作了概述,以期让更多的人了解中华水韭,促进我国水韭的进一步研究与保护。     

中华水韭(Isoetes sinensis)等位酶分析的初步研究

采用超薄平板聚丙烯酰胺等电聚焦技术对珍稀涉危植物中华水韭（Isoetes sinensis Palmer）72个样品的等位酶遗传变异进行了初步研究。从24种酶筛选,得到了13种酶系统可用于该植物的遗传变异分析,其中7种酶系统在中华水韭的迁地保护区群中检测出16个位点,共27个等位基因,12个位点表现出多态性。遗传多样性初步分析表明：中华水韭具较低的等位酶遗传多样性。研究结果为中华水韭的综合保育及居群恢复、重建提供了初步的依据。中华水韭遗传变异的全面研究将在进一步改善等位酶方法的基础上,采用其它更为灵敏的分子标记方法做深入检测。     

中华水韭雌配子体及胚胎发育的初步研究

中华水韭（Isoetes sinensis Palmer）属水韭科（Isoetaceae）草本拟蕨类,是长江中下游特有的古老物种,对环境污染敏感,为国家一级重点保护的极度濒危的野生植物。本研究通过人工培养,按不同发育阶段,用常规石蜡切片法连续观察了雌配子体及胚胎发育的全过程。结果显示：大孢子培养15～20 d萌发,雌配子体为球状、属壁内发育型,每个雌配子体着生8～20个颈卵器。成熟的颈卵器发育有多种可能,但只有颈沟细胞和腹沟细胞都退化,卵才有受精的机会。合子首先进行横向分裂,培养约50 d发育成数十个细胞的球形胚胎,约80 d雌配子体的细胞萎缩,第一叶及其叶舌、第一根结构更明显,出现第二叶。文中还初步探讨了中华水韭濒危的生殖生物学机制。     

浙江省中华水韭分布现状与濒危原因

中华水韭(Isoetes sinensis Palmer)为水韭科水韭属多年生沼泽植物,现分布范围急剧缩小,种群数量稀少,处于濒危状态。通过查阅文献、标本,咨询专家学者,深入实地考察,访问产地农民,基本弄清了中华水韭在浙江省的分布情况及现有种群状况,结果如下：据记载,中华水韭在浙江省分布在杭州、诸暨、松阳、庆元、丽水、建德和天台等市、县。但仅查阅到杭州(1号)、诸暨(2号)和松阳(1号)3地共4号标本。实地考察仅发现在松阳有2个野生亚种群;杭州、诸暨和丽水野生种群可能已灭绝;杭州植物园、武汉植物园目前迁地保存有杭州种群;天台是否有中华水韭分布尚存疑问。松阳2个野生亚种群总面积约1000m2,分布在4块废弃的水田中,海拔约1110m,居群集中分布的面积不到300m2。中华水韭生存生境的人为直接破坏及水体污染,是其种群消失的主要原因。中华水韭残存种群在与禾草和灯芯草(Yuncus effuses)等主要优势种的竞争中处于劣势,在群落演替过程中,可能会被这些物种所取代,进而整个群落有可能被其他植被所取代,故现有的2个亚种群正处于濒危状态,亟待加强保护研究。     

Genetic consequence of restricted habitat and population decline in endangered Isoetes sinensis (Isoetaceae)

BACKGROUND AND AIMS: Isoetes sinensis (Isoeteaceae) is a critically endangered aquatic quillwort in eastern China. Rapid decline of extant population size and local population extinction have occurred in recent years and have raised great concerns among conservationists. METHODS: Amplified fragment length polymorphisms (AFLPs) were used to investigate the genetic variation and population structure of seven extant populations of the species. KEY RESULTS: Eight primer combinations produced a total of 343 unambiguous bands of which 210 (61.2 %) were polymorphic. Isoetes sinensis exhibited a high level of intra-population genetic diversity (H(E) = 0.118; hs = 0.147; I = 0.192; P = 35.2 %). The genetic variation within each of the populations was not positively correlated with their size, suggesting recent population decline, which is well in accordance with field data of demographic surveys. Moreover, a high degree of genetic differentiation (F(ST) = 0.535; G(ST) = 0.608; theta(B) = 0.607) was detected among populations and no correlation was found between geographical and genetic distance, suggesting that populations were in disequilibrium of migration-drift. Genetic drift played a more important role than gene flow in the current population genetic structure of I. sinensis because migration of I. sinensis is predominantly water-mediated and habitat range was highly influenced by environment changes. CONCLUSIONS: Genetic information obtained in the present study provides useful baseline data for formulating conservation strategies. Conservation management, including both reinforcement for in situ populations and ex situ conservation programmes should be carefully designed to avoid the potential risk of outbreeding depression by admixture of individuals from different regions. However, translocation within the same regional population should be considered as a measure of genetic enhancement to rehabilitate local populations. An ex situ conservation strategy for conserving all extant populations to maximize genomic representation of the species is also recommended.     

中华水韭根叶发育的解剖观察

中华水韭(Isoetes sinensis Palmer)为国家一级保护野生植物,被评价为极度濒危级(CR),仅分布在长江中下游,对环境污染敏感。本文以其人工苗为材料,用石蜡切片法,连续观察了根和叶的发育特征:叶原基横切面呈端部渐圆的三角形,由表皮原、皮层原和中柱原三部分组成;维管束中央首先出现的一个原生管胞,与其近轴面两侧后出现的两个后生管胞共同组成倒“V”字型的外始式初生木质部;成熟叶分化出表皮与皮层,表皮细胞间有嵌合,皮层部分细胞裂解成彼此不相通的4个通气道。根横切面呈圆形,成熟区分化出表皮、皮层(外皮层、中皮层、内皮层)和维管束三部分,中皮层部分细胞裂解呈一个完整的筒状通气道并与外皮层无连接,由内皮层包围的维管束横切面呈三角形。讨论了根和叶的形态结构、功能及系统学意义。     

Analysis of genetic diversity in the endangered Hucho taimen from China

Hucho taimen are listed as endangered in China. The population size has declined recently, prompting an increase in the level of listing from grade three in 2002 to grade five in 2006. We analyzed the genetic diversity of wild populations using 17 microsatellite markers to establish a scientific basis for conservation of this species. We collected tissue samples from four populations in the Heilongjiang River basin: Huma River (HM), Hutou (HT), Haiqing (HQ), and Zhuaji (ZJ). A total of 21 loci were amplified, 18 of which were polymorphic. The number of alleles per locus ranged from 2 to 9 (mean: 4.1905). There were 13 highly polymorphic loci and 5 moderately polymorphic loci. Analysis of five genetic diversity parameters (Na, Ne, Ho, He, and PIC) suggested moderate levels of diversity within the populations. The populations were ranked HT > HQ > ZJ > HM, but the differences in diversity were not statistically significant (P > 0.05). A comparison of variation among all four populations suggested Hardy–Weinberg disequilibrium at 20% of the loci. Genetic differentiation (Fst) was 0.0644 and the gene flow among populations was estimated at 3.36 individuals per generation. The majority of diversity (93.88%) occurred among individuals within a population. In contrast, relatively little (6.12%) of the genetic diversity was distributed between the populations. An analysis of genetic differentiation and genetic distance between pairs of populations revealed that both parameters were higher in comparisons of the HM population to the HT, HQ, and ZJ populations than among the three latter populations. This suggests that the HM population has a distinct genetic structure. We hypothesize that habitat degradation and excessive fishing, not low genetic diversity, has caused the decline in H. taimen populations. However, this species should be protected from further declines in genetic diversity.     

Genetic diversity in Isoetes yunguiensis, a rare and endangered endemic fern in China

Isoetes yunguiensis is an endangered and endemic fern in China.Field survey indicated that only one population and no more than 50 individuals occur in the wild.The genetic variation of 46 individuals from the population remaining at Pingha (Guizhou Province,China)was assessed by Random Amplified Polymorphic DNA (RAPD)fingerprinting.Twelve primers were screened from sixty ten-bp arbitrary primers,and a total of 95 DNA fragments were scored.Of these,62.1%were polymorphic loci,which indicated that high level genetic variation existed in the natural population.The accumulation of genetic variation in the history of the taxon and the apparent minimal reduction effect on genetic diversity following destruction of habitat might be responsible for the high level genetic diversity presently remaining in the I.yunguiensis population.However,with the continuing decrease of population size,the genetic diversity will gradually be lost.We suggest that the materials from the extant population should be used for re-establishment of the populations.