用EST-SSR检测不同年代小麦育成品种基因多样性的变化趋势

EST—SSRs是一种基于基因表达序列有关基因功能的“真质”标记，其多态性直接反映了基因的多样性。本研究采用37对小麦EST—SSRs引物检测了42份我国不同年代小麦选育品种相关基因位点多样性的变化趋势。结果表明：基于表达序列设计的小麦EST—SSRs引物具有较好的扩增效果，其中37对引物共检测到134个位点，绝大多数引物有2～5个等位变异；在相似系数为0.9的水平上这些引物可将除燕大1817和旱选3号外的40份材料区分开来；供试的42份小麦选育品种的基因多样性从20世纪60年代以前到90年代呈递增趋势，但不同年代的增幅不同：20世纪60～80年代增长最快，80年代至90年代增长十分缓慢；同时，材料间相似系数变化呈下降趋势，60年代以前的选育品种相似性最高，70年代最低，70年代以后至90年代略有增加，但远低于60年代以前，这与引人大量的外来品种的育种策略有关。

Changes of Gene Diversity Among Chinese Wheat Cultivars at Different Decades Revealed by EST-SSRs

SSRs developed from expressed sequence tags (EST-SSRs) are relevant to gene functions.Therefore,the polymorphism of EST-SSR markers in a population might reflect the diversity of related genes directly.In this study,37 sets of EST-SSR markers were used to analyze the gene diversity among 42 Chinese wheat cultivars applied at different decades.The results demonstrated that most primers amplified very clear and strong fragments with expected size.Totally,the 37 loci generated 134 alleles,and most of the loci had 2 to 5 alleles.Forty varieties were discriminated clearly at the similarity coefficient (0.9),which implied that some cultivars could be identified by certain primer pairs according to the specific PCR amplifications.For the 42 wheat cultivars,the gene diversity increased from 1960s to 1990s,the highest occurring in 1970s.On the contrary,the similarity coefficients decreased from 1960s to 1990s,lowest in 1970s,then it increased slowly till now,but still lower than in 1960s.It was suggested that the introduction of many alien genes or chromosome fragments to local varieties might contribute to the trends of genetic diversity.