Reciprocal recurrent selection effects on the genetic structure of tropical maize populations assessed at microsatellite loci

Genetics and Molecular Biology

Luciana Rossini Pinto²  Maria Lucia Carneiro Vieira²  Claudio Lopes De Souza Jr.²  Anete Pereira De Souza¹ 

[1] ,Universidade de São Paulo Escola Superior de Agricultura 'Luiz de Queiroz' Departamento de GenéticaPiracicaba SP ,Brazil

关键词: population genetics;    plant breeding;    molecular markers;   

DOI  :  10.1590/S1415-47572003000300022

来源: SciELO

【 摘 要 】

A modified reciprocal recurrent selection (RRS) method, which employed one cycle of high-intensity selection, was applied to two tropical maize (Zea mays L.) populations, BR-105 and BR-106, originating the improved synthetics IG-3 and IG-4, respectively. In the present study the effects of this kind of selection on the genetic structure of these populations and their synthetics were investigated at 30 microsatellite (SSR) loci. A total of 125 alleles were revealed. A reduction in the number of alleles was observed after selection, as well as changes in allele frequencies. In nearly 13% (BR-105) and 7% (BR-106) of the loci evaluated, the changes in allele frequencies were not explained, exclusively due to the effects of genetic drift. The effective population sizes estimated for the synthetics using 30 SSR loci were similar to those theoretically expected after selection. The genetic differentiation (G ST) between the synthetics increased to 77% compared with the original populations. The estimated R ST values, a genetic differentiation measure proper for microsatellite data, were similar to those obtained for G ST. Despite the high level of selection applied, the total gene diversity found in the synthetics allows them to be used in a new RRS cycle.

【 授权许可】

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