宁夏不同年代水稻品种的遗传多样性比较

Comparative Analysis of Genetic Diversity for Different Period Rice Varieties in Ningxia

对宁夏不同阶段主栽水稻品种（系）的主要农艺性状比较表明,第1阶段（1950-1962年）宁夏地方品种与第2阶段（1978-1989年）、第3阶段（1990-1999年）、第4阶段（2000-2005年）、第5阶段（2006-2012年）、第6阶段（2010-2013年）育成品种（系）的农艺性状差异显著,说明通过育种手段宁夏水稻品种的主要农艺性状得到了改良；从第2阶段到第6阶段的变化趋势为生育天数变长,有效穗数减少,穗长、穗粒数、单株粒重、单穗粒重、产量等增加,说明产量性状的育种改良从穗数型向穗粒兼顾型或穗重型发展。利用48对SSR引物对76份宁夏不同年代水稻品种（系）进行遗传多样性分析表明,共检测出290个等位基因,每个位点等位基因变幅为3～15个,平均6.04个；稀有等位基因有109个,占等位基因总数的37.59%；多态信息含量（PIC）变异范围为0.1423～0.8783,平均为0.5512；Nei’s基因多样性指数（He）的变幅为0.1492～0.8945,平均为0.6032。RM333、RM297、RM249、RM501和RM206引物表现为较高的等位基因数和稀有等位基因数,认为较适合应用于宁夏水稻品种的遗传多样性检测。分子方差分析（AMOVA）结果表明,6个不同阶段间遗传变异占总体变异的19.27%,各阶段内品种间的遗传变异占总体变异的80.73%。参试水稻UPGMA聚类分析表明,在遗传相似系数（GS）为0.805处可将其划分为5大类群,12个地方品种都被聚为第Ⅰ类群,具有外来引进血缘的8个常规粳稻品种被聚为第Ⅱ类群,5个优质常规粳稻被聚为第Ⅲ类群,第Ⅴ类群包括2个大穗高产品种,49个宁夏常规粳稻选育品种被聚为第Ⅳ类,说明大多数宁夏水稻品种的亲缘关系较近。6个不同阶段品种聚类分析,第1阶段（地方品种）独聚一类,第2、第3、第4阶段与第5、第6阶段育成品种亲缘关系相对较远；表明不同年代宁夏水稻遗传多样性有较大差异,2005年后宁夏水稻品种的遗传多样性趋于变小。宁夏水稻育种中应加强国内外种质资源的引进和利用,深入挖掘宁夏稻区地方品种和杂草稻资源的有利基因,拓宽宁夏水稻品种的遗传基础,以促进宁夏水稻育种的快速发展。

The comparision of main agronomic traits of different stage rice varieties（ strains） commercially grown in Ningxia showed the significant difference of agronomic characters between the first stage（ 1950-1962） and the second（ 1978-1989）,the third（ 1990-1999）,the forth（ 2000-2005）,the fifth（ 2006-2012）,the six（ 2010-2013） stage. This meaned that the agronomic traits of rice varieties in Ningxia was improved by breeding techniques. There was a decreasing trend of effective panicle and an increasing trend of days of growth period,pani-cle length,spikelets per panicle,weight per panicle,weight per plant,and grain yield from the second stage to the sixth stage were found. The pattern of breeding of grain yield traits became to panicle weight type or both of panicle and spikelet type from panicle number type. The analysis of the genetic diversity of 76 rice varieties bred in different period of Ningxia by using 48 polymorphic simple sequence repeats（ SSR） markers showed that there was 290 alleles were detected,and the number of alleles per pair of primers ranged from 3 to 15 with a mean value of 6. 04. Among which,109 alleles（ 37. 59%） were minor alleles. RM333,RM297,RM249,RM501,and RM206 showed higher score of alleles and minor alleles,which were suitable to assess the genetic diversity of rice varieties from Ningxia. Polymorphic information content（ PIC） ranged from 0. 1423 to 0. 8783 with a mean value of 0. 5512. The Nei＇s genetic diversity index（ He） ranged from 0. 1492 to 0. 8945 with a mean value of 0. 6032. The cluster analysis of six stages of rice results of analysis of molecular variance（ AMOVA） indicated that the genetic variation among the six stages was accounted for 19. 27% of the total genetic variation,which the genetic variation among the varieties during every stage was accounted for 80. 73%. The UPGMA cluster analysis of 76 rice varieties in Ningxia showed that there were five categories clustered in the 0. 805 level of genetic similarity coefficient. Twelve rice landraces were clustered into groupⅠ. GroupⅡ included eight conventional japonica rice varieties,which had blood relationship with foreign varieties. Group Ⅲ included five high quality rice improved varieties. Group Ⅴincluded two large-panicle and high-grain yielding improved cultivars. 49 conventional japonica rice varieties were clustered in group Ⅳ,it showed that majority rice varieties in Ningxia had a closer genetic relationship. Group varieties in Ningxia showed that the first stage（ Landrace） was clustered into a separate category. The relationship was relatively distant between the second,the third,the forth stage and the fifth,the six stage. The results showed that there was greater differences of genetic diversity among the six different periods,and the genetic diversity decreased after 2005. In order to accelerate the rice breeding process in Ningxia,we should strengthen the introduction and use of rice germplasm resources from other provinces and abroad,explored the favorable genes from rice landrace and weedy rice in Ningxia,and broaden the genetic basis in order to improve the rapid development of rice breeding in Ningxia.