engleski

The effect of recurrent selection on genetic structure of a synthetic maize population

The Maksimir 3 Synthetic maize population (Zea mays L.) was created by intercrossing of 12 domestic inbred lines, which origin traces back to several landraces. The population underwent four cycles of recurrent selection for grain yield and lodging resistance. The objective of the present study was to examine the effect of selection on simple sequence repeat (SSR) marker allele frequencies and population structure. The SSR analysis revealed no significant changes in the mean number of alleles per locus and the mean expected heterozygosity after four cycles of selection. The proportion of selectively nonneutral loci in single cycles of selection, based on Waples’ test of selective neutrality, varied between 16% and 37%. Some of nonneutral loci co-located with previously published QTLs controlling important agronomic traits. Between 5% and 29% of loci were found to be in significant Hardy- Weinberg (HW) disequilibrium with majority of them showing an excess of homozygosity. Excess of homozygosity at several loci was highly consistent across cycle populations suggesting positive assortative mating as the possible cause of the observed HW disequilibrium. Linkage disequilibrium (LD) test was not significant for the most pairs of SSR loci. The proportion of pairs of loci in significant LD varied across cycles of selection between 0.1% and 1.8% probably due to the effects of genetic drift and epistatic selection.

Maize, SSR, LD, recurrent selection

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