Genetic Diversity of Maize Populations Developed by Two Kinds of Recurrent Selection Methods Investigated with SSR Markers

Lu-jiang LI.K.-cheng YANG.G.ang-tang RONG

Agricultural Sciences in China 7(9): 1037-1045


ISSN/ISBN: 1671-2927
DOI: 10.1016/s1671-2927(08)60144-3
Accession: 022703484

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Two cycles of biparental mass selection (MS) and one cycle of half-sib-S3 family combining selection (HS-S3) for yield were carried out in 2 synthetic maize populations (P4C0 and P5C0) synchronously. The genetic diversity among 8 maize populations, including the basic populations and their developed populations, was evaluated using 30 simple sequence repeat (SSR) primers. On the 30 SSR loci, 184 alleles were detected in these populations. In each locus, the number of alleles varied from 2 to 14 (6.13 on average). The number and ratio of polymorphic loci in both basic populations were higher than those in the developed populations. The mean gene heterozygosity did not significantly vary after MS, but decreased after HS-S3 in both basic populations. The mean genetic distance varied slightly after MS, but decreased at a greater degree after HS-S3 in basic populations. The range of genetic distance was wider after MS, and the genetic distance between populations developed by HS-S3 was generally lower than that in both basic populations. The number of genotypes increased after MS but decreased after HS-S3 in both basic populations. The intra-population genetic diversity was much more than the inter-population genetic diversity in both basic populations. All the indexes demonstrated that the genetic diversity among the populations after MS was similar to that of the basic populations. The genetic diversity was maintained during MS, but was reduced after HS-S3, indicating that heterogeneity between some of the individuals in the developed populations increased after MS, whereas the populations became more homozygotic after HS-S3.