SSR标记揭示的云南地方稻品种遗传多样性及其保育意义

为了探索水稻(Oryza　sativa　L.)地方品种的遗传多样性及其有效保育方法,对采自云南省17个村寨的82个水稻地方品种和3个国际常用的典型籼稻和粳稻品种进行了微卫星(SSR)分子标记的分析。利用19对SSR引物在85个水稻品种中共扩增出了83个基因型,其分子量变异在100～500　bp之间。基于各品种SSR基因型遗传相似系数聚类分析而获得的UPGMA树状图表明各水稻品种之间存在较大的遗传多样性,其相似系数变异在0.15～0.90之间。但这些地方品种的遗传多样性并非呈均等的地理分布。这85个水稻品种在相似系数为0.52之处分为二组,其中一组包括几乎所有的籼稻品种,而另一组包括全部的粳稻品种,表明SSR标记能很好揭示水稻籼-粳分化。同时,有些来自不同采集地的同名品种表现出一定的遗传差异,说明同名异物的现象存在。云南水稻地方品种具有丰富的遗传多样性,对其有效保育十分重要和迫切,　但只有根据遗传多样性的水平和分布特点,采用正确的保育对策和取样方法才能确保对云南水稻地方品种的有效保育。结果进一步表明,选用适当的微卫星引物,可以为准确鉴定籼稻和粳稻品种及研究其进化规律提供有效的分子标记方法,并有利于有目标的水稻遗传资源保育和育种创新。

Estimating Genetic Diversity of Rice Landraces from Yunnan by SSR Assay and Its Implication for Conservation

Eighty-five rice (Oryza sativa L.) varieties, including 82 rice landraces collected from 17 villages in Yunnan Province of China and three standard varieties representing typical Indica and Japonica ecotypes, were studied using simple sequence repeat (SSR) markers to estimate their genetic diversity for the purpose of strategic conservation. Nineteen selected SSR primer pairs amplified a total of 83 SSR alleles, with molecular weight ranging from 100 to 500 bp, from the 85 rice varieties. An UPGMA dendro- gram based on the cluster analysis of genetic similarity of the SSR alleles showed a significant genetic variation among the included rice varieties, with the similarity coefficients varying between 0.152 and 0.900. However, genetic diversity of the rice varieties collected from Yunnan was unevenly distributed over their geographical locations. Two distinct groups were identified from the cluster analysis of the 85 rice varieties at the similarity coefficient level of 0.152, with one group that included almost all accessions of Indica ecotype and another group that contained all accessions of Japonica ecotype. Varieties that shared the same names but collected from different villages did not always show a close genetic relationship, indicating misidentification of some varieties by local farmers. It is concluded from this study that conser- vation of genetic diversity in rice landraces is urgently necessary in Yunnan, given their high level of diversity, but an appropriate strategy needs to be followed to guarantee the effectiveness of conservation activities. Properly selected SSR primer pairs might provide an ideal method for identifying Indica and Japonica ecotypes for rice conservation and breeding programs.