Revista Brasileira de Milho e Sorgo (Dec 2005)
RECOVERY OF RECURRENT GENOTYPE IN MAIZE USING SSR MARKERASSISTED BACKCROSS
Abstract
This work was carried out to evaluate the use of microsatellite markers to accelerate the recovery of recurrent genome in maize backcross breeding programs. An inbred line with high general combining ability for grain yield and high ear insertion (L11) was used as recurrent parent, and a maize inbred line with low ear height and low grain yield in crosses (L3) was used as the donor parent. Phenotypic selection for low ear insertion was performed in two backcross cycles, and the recover of the recurrent genotype of selected plants was monitored using SSR markers. The objective of this work was to compare the recovery of recurrent parent genotype in backcross progenies selected for low ear insertion, with and without marker-assisted selection. For this purpose, grain yield of these progenies were evaluated in topcross hybrids with a tester line (L161) in three locations. Results indicated that SSR markers were efficient in identifying individuals with a high proportion of the recurrent genome after the first two BC generations, allowing a gain of up to three generations compared to the theoretical recovery predicted in conventional backcross. Phenotypic selection for low ear insertion was efficient, although there was an incomplete recovery of the donor phenotype (L13) after two backcross generations. We obtained topcross hybrids from the progenies derived from markerassisted backcross showing higher yield and lower ear insertion than the recurrent topcross hybrid. However, our experimental conditions did not allow further conclusions about using the grain yield of topcross hybrids to evaluate the recovery of recurrent parent genome in backcross programs in maize.
