【作者】 张剑锋；

【导师】 刘宝；

【作者基本信息】 东北师范大学 ， 遗传学， 2009， 博士

【摘要】 本论文采用AFLP(amplified fargment length polymorphism)和MSAP(methylation-sensitive amplified polymorphism)两种DNA分子标记技术,对中国东北松嫩平原4个属同一个生态型(灰绿型)羊草(Leymus chinensis(Trin.)Tzvel.)天然种群48个单株,进行了遗传与表观遗传多态性和遗传结构的分析,并对这两种分子标记的结果进行了比较。主要研究结果如下:利用AFLP分子标记,对松嫩平原4个羊草天然种群的遗传多态性和遗传结构的3个遗传多态性指标、基因流、遗传距离、分子方差分析(AMOVA)、Jaccard相似性系数(JSI)分析、非加权分组平均法(UPGMA)聚类分析和主坐标分析(PCA)等项研究表明,羊草种群遗传多态性和遗传结构变化的趋势是一致的,羊草种群分布符合距离隔离模型。除地理距离外,其它物理和/或生物因素也是造成遗传隔离,引起种群遗传分化的主要原因。CC种群成为栖息地碎片(habitatfragmentation),个体间逐渐形成均质性就是一个典型的例子。松嫩平原4个羊草天然种群的MSAP分析结果表明,甲基化变异模式具有种群特异性,同时种群间也存在甲基化变异,但程度不同。甲基化敏感多态性(MSP)与甲基化不敏感多态性(MISP)有显著的相关性(r=0.8370),羊草DNA甲基化多态性变化的两种类型是相互影响和制约的,即任何一种类型变异的发生都会导致另外一种类型变异的发生。将AFLP与MSP和MISP进行比较发现,AFLP相似度比MSP和MISP要高出很多,说明羊草DNA甲基化多态性虽然可能受遗传变异的影响,但同时具有独立的产生和维持机制。AFLP、MSP和MISP的UPGMA聚类分析和PCA分析表明,种群CC和BT(土壤pH值均为7)以及ZL和Cb(土壤pH值均为8.5-9.5)分别被聚得比较接近,说明可能是由不同盐碱条件下的胁迫引起栖息地的异质性使其产生可遗传的表观遗传变异造成的。更多还原

【Abstract】 Genetic diversity and genetic structure of four Leymus chinensis (Trin.) Tzvel. (Poaceae) populations (with the same ecotype, Grey-Green Leaf), which comprised of a total of 48 clones collected from the Songnen plain in northeastern China were analyzed by amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP) markers. The efficiency of the two markers was evaluated.Indices of genetic diversity, gene flow, genetic .distance, AMOVA, JSI analysis, the UPGMA cluster analysis and PCA generated from AFLP marker had the same trends. The spatial structure of the four populations was consistent with the stepping stone model. It can be envisioned that multiple other factors might have imposed their influence on the efficiency or effectiveness of gene flow among the L. chinensis populations. The CC population, as habitat fragmentation, was seen as being isolated due to its special predicament of its locality. Being in the midst of tall buildings seems to have raised a great barrier which is gradually isolating it from the rest. The exceptionally low level of gene flow between CL and CC populations provided a typical example to suggest that genetic isolation is not necessarily determined by geographical distance; instead, other factors could also have played a role in the differentiation of these populations although physical and/or biological isolation seem to be the most significant.In MSAP analysis, it was found that methylation pattern of L. chinensis populations in Songnen plain is characteristic of each population. The correlation between MSP (methylation-sensitive polymorphism) and MISP (methylation-insensitive polymorphism) influences and restricts each other, as a result, from Mental test of JSI matrices of them(r = 0.8370), they are likely affecting each other.Because JSI of AFLP is higher than that of MSP and MISP, the DNA methylation pattern change of L. chinensis is not only related to DNA sequence variation, but also likely being regulated by additional controlling system(s). The UPGMA cluster analysis and PCA from AFLP, MSP and MISP showed that a close link between the clones grown in the same abiotic conditions. Like CC was more closely related to BT (all grown at pH 7) and CL more closely linked to ZL which are grown in soils of pH 8.5-9.5. Thus, the possibility of habitat inducement can not be ruled out in causing heterogeneity in stressful conditions of varied salinity/alkaline which is known to cause heritable epigenetic variations in plants.更多还原