Utility of molecular markers in hybrid corn breeding
2003
Guzman, P.S. | Coronado, N.B. | Hautea, D.M. (Philippines Univ. Los Banos, College, Laguna (Philippines). Dept. of Agronomy)
Heterotic groups and heterotic patterns are tools to exploit heterosis in hybrid corn breeding. Knowledge of heterotic pattern makes hybrid breeding more defined and systematic. Heterotic patterns can be established using diallel analysis but the procedure is tedious, time-consuming and costly, particularly if many lines or populations are involved. Molecular markers such as Simple Sequence Repeat (SSR) have been used effectively to measure molecular genetic diversity in many crops including maize. The extent of genetic diversity has been associated with heterotic performance. The objectives of our study were to determine the genetic diversity among 33 yellow inbred lines using SSR, and to verify the clusters generated based on genetic divergence as potential heterotic groups using diallel analysis. Thirty-three inbreds were assayed for polymorphism at 60 selected SSR loci using agarose gels. One hundred thirty two alleles were identified and used to estimate genetic dissimilarity among the lines. Cluster analysis placed the inbreds into five distinct groups. Diallel crosses were formed by selecting representative lines from four groups. The 10 parents, the 45 F1s and one check were evaluated in a 7x8 rectangular lattice with two replications at one and two locations in 2000 and 2001, respectively. Analysis showed that in general, average F1 performance and estimates of SCA and mid-parent heterosis for grain yield were higher in inter-group than intra-group crosses. Results suggest that the clusters generated by SSR correspond to heterotic groups, which would be useful to exploit heterosis in our breeding program leading to the development of superior hybrids
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