Determination of the Sample Size in Sorghum (Sorghum bicolor L.Moench.)Genetic Integrity Analysis with Microsatellites
Sorghum {Sorghum bicolor L. Moench. } is one of the world's most important cereals. There are a-bout 19 000 seed accessions of sorghum in national genebank of China now. One of the main challenges for gene-banks is the maintenance of the genetic integrity of seed accessions. The study of genetic integrity of sorghum as often cross-pollinated crops has not been reported yet. In order to assess genetic integrity of sorghum correctly, firstly, it is supposed to determine the sample size. Molecular markers are supposed to be the most effective genetic tools for the actual estimate of genetic integrity and microsatellites or simple sequence repeats (SSRs) are one of the most commonly used markers in genetic diversity assessment, population structure studies and marker-assisted selection. To determine the optimal sample sizes of genetic integrity of sorghum , in our study, ten groups of different sample sizes of sorghum (10,20,30,40,50,60,70,80,90,100 individuals per group) were set by random selections and 25 polymorphic microsatellite primers were used to assess the genetic diversity indexes (the average number of alleles, effective number of alleles ,Shannon index,observed heterozygosity .expected heterozygosity, percentage of polymorphic loci and the frequency of rare alleles). Correlation between genetic diversity indexes and sample sizes were analyzed and the results demonstrated that the number of alleles, effective number of alleles, Shannon index increased dramatically with the increase of sample sizes within 40 individuals, and they increased slowly and reached a plateau when more than 40 individuals analyzed. Forty individuals represented 98. 5% of total numbers of alleles,99. 1% of total effective numbers of alleles and 98. 5% of total Shannon indexes of 100 individuals. With the number of alleles, effective number of alleles, Shannon index and the frequency of rare alleles as genetic diversity indexes in the study of sorghum genetic integrity, determination of the sample sizes reached consistency. Therefore, we suggest that the optimal sample size for the study of sorghum integrity with microsatellites analysis is 40 individuals. This study will facilitate the study of genetic integrity of sorghum.
国家科技期刊平台
NSTL
万方数据
维普
