Recurrent selection effects on the genetic structure of maize landrace assessed by SSR markers

Abstract

Recurrent selection method was applied in one maize landrace (Zea mays L.) population, Macaco, for one cycle of selection. In the present study the changes in genetic structure were investigated at 18 microsatellite loci. A total of 81 alleles were observed in cycle 0 (C0) population which 79 were maintained in cycle 1 (C1) population. Thus, a reduction of 2.5% in the allele frequency was observed after one cycle of selection in C1 population. The heterozygozity reduction was also observed after one cycle of selection. In nearly 44% and 55% of the loci evaluated in C0 and C1 populations, respectivelly, the changes in allelic frequencies in populations were not due exclusively by genetic drift effects. Although few changes have been observed in allelic frequencies, the grain yield increase was observed after one cycle of recurrent selection. The genetic differentiation estimated by GST and RST values, for microsatellite data between C0 and C1 populations indicate that genetic variability degree was maintained in C1 population. This result suggest that C1 population can be used in a new recurrent selection cycles.