1999—2001年中国主要玉米杂交种遗传基础的变化趋势及三大种质类群在育种中的应用

Trends in Genetic Diversity Among Widely used Inbreds from 1991 to 2001 in China and Application of Three Major Germplasm Groups in Maize Breeding

【目的】研究10年来中国主要玉米杂交种遗传基础的变化趋势及分析四平头、Reid和Lancaster三大种质类群等位基因的变异,为中国玉米育种提供一些理论依据。【方法】利用111个SSR标记对1991—2001年间大面积推广的66个杂交种的84份亲本自交系进行分析。【结果】①在66个杂交种中共检测到659个SSR等位基因,平均每个位点检测到5.95个等位基因。在过去的10年间,大面积推广的杂交种Nei遗传多样性指数由0.67增加到0.69,可检测到的等位基因的数量逐年增加,由603增加到653个等位基因,2001年大面积推广的杂交种与1991年的杂交种相比,缺失的等位基因仅有0.9%,而新增加了8.5%的等位基因;②对其中的四平头类群自交系16份,Reid类群15份自交系和Lancaster类群8份自交系进一步分析发现,在39个玉米自交系中共检测到583个等位基因,占检测到的SSR位点等位基因总数的88.3%。其中四平头类群检测到的等位基因位点最多,占检测到的等位基因总数的77.4%,Reid类群和Lancaster类群差别不大,分别为61.5%和60%。Reid与四平头及Lancaster与四平头的等位基因差异均在32%左右,而Reid与Lancaster间等位基因的差异仅为25%。而且Reid与Lancaster类群提供的特有等位基因比率分别为7.9%和7.3%,大部分的特有等位基因存在于四平头类群,约为24%。【结论】随着新的种质资源的引入和对原有资源的改造,与20世纪90年代初相比,中国的玉米资源遗传多样性有了一定的增加;地方种质含有大量的特有等位基因,这是其与国外种质组配优异杂交种的重要基础,应当加强地方种质的改良和利用。

[Objective] To investigate the trends in genetic diversity among widely used inbreds from 1991 to 2001 in China and to compare genetic variation among three major germplasm groups. [Method] In this paper, 88 inbreds of 66 maize hybrids which widely used commercially in 1991 through 2001 were used to analyze the changing trends of the genetic base with 111 SSR markers. [Result] Firstly, 659 SSR alleles were detected in 66 hybrids with the average of 5.95 per locus. Nei＇s genetic diversity index of the widely extended hybrids during the past decade was increased from 0.67 to 0.69 and the allele number increased from 603 to 653. Only 0.9% absent alleles but 8.5% new alleles were detected by comparing the hybrids in 2001 with those released in 1991. Secondly, there were 583 alleles detected with 111 S SR markers in 39 inbreds including 16 from SPT group, 15 from Reid and 8 from Lancaster. Of which the alleles detected in SPT group were the most and took the percentage of 77.4%, Reid and Lancaster groups were 61.5% and 60%, respectively. The alleles frequency difference between Reid and SPT, Lancaster and SPT was both at about 32%, but the frequency difference between Reid and Lancaster was only 25%. Most of the special alleles existed in SPT group （24%）, and Reid and Lancaster groups provided fewer （7.9% and 7.3%, respectively）. [Conclusion] With the introduction of new germplasm and improvement of the old germplasm, the genetic diversity of maize hybrids was not decreased but increased to some extent. There are many unique alleles in local germplasms which maybe become the genetic base to produce elite hybrids when crosses with those abroad. So it is necessary to pay attention to the improvement and utilization of domestic germplasm.