云南金钱槭形态变异与遗传变异的相关性研究

Researches on the relationship between the morphological and genetic variations of Dipteronia dyeriana Henry (Aceraceae)

对我国特有珍稀濒危保护植物云南金钱槭的形态变异水平、遗传变异模式以及两者之间的相关性进行了研究。形态学性状分析结果表明 :各居群形态性状变异系数的平均值从大到小排列为 :文山居群 (WSh)、屏边居群 (PB)、黑龙潭居群 (HL T)、蒙自居群 (MZ) ;文山居群与屏边、黑龙潭、蒙自居群间已产生显著或极显著水平的形态差异 ,而后三者间的差异未达显著水平。RAPD分析检测到 10 3个位点 ,其中多态位点 84个 ,云南金钱槭物种水平的多态位点比率为 81.5 5 % ,与其它珍稀濒危植物相比该种的遗传多样性水平不低。 AMOVA和 N ei基因多样性指数分析显示 ,尽管大部分遗传变异仍存在于居群内 (分别为5 7.86 %、5 7.33% ) ,但居群间的遗传变异已达较高水平 (分别为 4 2 .14 %、4 2 .6 7% )。相关分析结果显示 ,云南金钱槭的形态变异与海拔、土壤有机质等生态因子有着显著或极显著水平的相关性 ,但与遗传变异的相关性未达显著水平 ,说明云南金钱槭的形态变异虽然具有一定的遗传基础 ,但可塑性及环境压力对形态变异的产生作用更大一些。基于形态性状和 RAPD数据的聚类分析则进一步说明 。

Dipteronia dyeriana Henry is a rare and endangered species of China. Four populations, collected from Wenshan (WSh), Mengzi (MZ), Pingbian (PB) and Heilongtan (HLT) respectively, were used for the research on its morphological variation, its pattern of genetic variation, and the correlation between them. 27 macro-scopic and micro-scopic morphological characters, including those of branches, leaves, fruit and seeds, were measured. The results showed that, according to the mean variation coefficients of the morphological characters, the order of the variation level of the 4 populations was in turn WSh>PB>HLT>MZ. There existed significant or remarkably significant morphological differentiations between WSh and other three populations. However, those differentiations among the latter three populations failed to reach a significant level. Based on RAPD markers, 103 loci were amplified with 18 primers, of them 84 were polymorphic. The proportion of polymorphic loci was 81.55% at the species level, and thus the genetic diversity of Dipteronia dyeriana Henry wasn't lower than other rare and endangered plants. AMOVA and Nei's genetic diversity index analysis showed that, though relatively high genetic variations(57.86% and 57.33% respectively) existed within populations, there were rather high differentiation among populations (42.14% and 42.67% respectively). Results of correlation analysis showed that there existed correlations between Dipteronia dyeriana Henry's morphological variations and ecological factors such as altitude, soil organic matters, etc. Different ecological factors exerted different influences on morphological variations and comprehensive effects by various ecological factors were supposed to be responsible for the morphological differentiations. Results of correlation analysis between the genetic variations and ecological factors such as soil water content and annual precipitation showed that there existed a clear negative correlation between genetic variations and factors such as soil water content and annual precipitation. Water condition of the habitats may have played a comparatively important role in the maintenance of Dipteronia dyeriana Henry's genetic diversity. Correlation analyses were also performed between the variation coefficients of morphological characters and three genetic diversity indices including proportion of polymorphic loci, Shannon diversity index and Nei's gene diversity index. The results showed that there existed positive correlations between variation coefficients of morphological characters and the three genetic diversity indices. However, results of the significance test revealed that none of the correlations reached the significant level (P>0.05). This indicated that, although morphological variation had its genetic basis to some extent, plasticity and environmental pressure influenced the morphological variation more intensively. Clustering analyses based on morphological characters and the RAPD data further revealed that the Dipteronia dyeriana Henry's morphological variations were intensively influenced by the environmental factors, while its correlation with the population genetic background was not significant.