Articles

Revealing core heterotic germplasm and characterizing of maize inbred lines using SSRs


Abstract


Clear knowledge about germplasm characteristics of inbred lines is very important for breeding and genetic research in maize. In this study, a total of 100 SSR markers uniformly distributed on all chromosomes were used to classify 758 lines with broad germplasm types and to reveal the germplasm relationship of 452 introduced lines with unknown pedigree and 91 lines from different sources. Great genetic diversity was observed among these lines, with total alleles 384, alleles per locus 2 ~ 11, polymorphic information content 0.23 ~ 0.86, gene diversity
0.26 ~ 0.88, major allele frequency 0.09 ~ 0.50. All lines were divided into 10 groups G1~G10, in which all lines with unknown pedigree were included. Five typical heterotic groups were revealed. Three groups (G1, G2, and G7, totally included 695 lines, accounting for 91.69%) and two core heterotic types (G1×G2 and G7×G2) were consistently revealed according to typical lines, the genetic differences among different groups and between pairs of parental lines for 48 important commercial hybrids. Eighteen high-oil and 18 popcorn lines were distinctly classified in G7-9 and G8 groups. The namesake lines from different sources were classified into the same groups for
82 lines, while other 9 such lines were classified into different groups or subgroups. In addition, line improvement among typical groups was obviously reflected and proved to be the effective way in further maize breeding. These results were mainly consistent with inbred pedigree/heterotic groups, previous researches and breeding practice, and could provide useful gerplasm information for all lines in further maize breeding and genetic research.

Keywords

maize, inbred line pedigree, germplasm characterization, heterotic type, genetic diversity, SSR markers

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