我国水稻主栽品种SSR多样性的比较分析

A Comparative Study on SSR Diversity in Chinese Major Rice Varieties Planted in 1950s and During the Most Recent Ten Years

采用40个SSR标记,比较分析了151份20世纪50年代(78份)和近10年(73份)我国常规稻主栽品种的遗传差异,发现有39个标记具有多态性,多态性位点共检测到213个等位基因,每个位点2～11个,平均5.5个;平均Nei基因多样性指数(He)为0.649,范围在0.309(RM174)～0.869(RM418)。籼粳亚种间SSR多样性差异明显,籼稻平均等位基因数(Na)和Nei基因多样性指数(Na=4.4,He=0.458)均高于粳稻品种(Na=4.0,He=0.395)。比较了78份20世纪50年代与73份近10年水稻主栽品种的遗传多样性,籼、粳亚种表现出相近的变化趋势,即Nei多样性指数和等位基因数20世纪50年代主栽品种高于近10年的。虽然Nei基因多样性指数的变化并不显著(籼稻:z=1.471,P=0.141;粳稻:z=1.932,P=0.053),但等位基因数目的变化达到显著水平(籼稻:z=2.677,P=0.007;粳稻:z=3.441,P=0.001)。分子方差分析(AMOVA)表明,遗传变异绝大部分存在于两时期内,尽管时期间平均贡献的遗传变异仅占1.9%,但仍然达到5%的显著水平;籼、粳亚种两时期间平均贡献的遗传变异高于整个分析样本,分别为5.0%和8.2%;籼、粳亚种不同位点的遗传分化程度也各不相同,籼稻和粳稻品种分别有13个(占33.3%)和11个(占28.2%)SSR位点的等位基因在两时期间差异显著,而其余位点的遗传变异则是因时期内品种间的差异引起的。研究表明近10年我国常规稻主栽品种丢失了一部分等位基因,水稻育种仍应加强更广泛的种质亲本的选择。

A total of 40 SSR markers were used to compare the genetic diversity in 151 Chinese major rice varieties planted in 1950s and during the most recent ten years. Of the 40 SSR loci, 39 were polymorphic while 1 locus （RM479） was found to be monomorphic. All the 39 polymorphic loci revealed a total of 213 alleles. The mean number of alleles per locus （Na） was 5.5 with a range from 2 to 11. Total genetic diversity index of Nei （He） varied greatly among loci from 0. 309 at RM174 to 0. 869 at RM418, with an average value of 0. 649. There existed a significant difference in SSR allelic diversity between indica and japonica subspecies. Indica rice had more variation than japonica rice both for Na and He. By comparison of the genetic changes in Na and He, it was found that varieties planted in 1950s had more alleles and higher He than those in recent ten years both for indica and japonica rice. The difference between two subspecies was significant in a tendency for Na over time （indica： z = 2. 677, P = 0.007; japonica： z = 3. 441, P =0.001）, but not for He （indica： z = 1. 471, P = 0. 141 ; japonica： z = 1. 932, P = 0.053）. Analysis of molecular variance （AMOVA） indicated that the genetic variation was significantly different （P 〈 0.05） between the periods of the 1950s and the recent ten years, of which, more genetic variation was contributed by indica （Fst = 0.050） and japonica （Fst = 0. 082） subsets. Using locus-by-locus AMOVA procedure, significant differentiations were observed in 13 loci for indica subset and 11 loci for japonica subset between periods. It was found a part of the ge- netic alleles was lost in current major rice varieties as comparison with those of 1950s. Therefore, more alien elite genetic resources should be explored in the current program of Chinese rice breeding.