Association Mapping for Flowering Time and Moisture Loss of Grains in Maize Tropical Germplasm

With the advent of high-scale genotyping platforms, association studies have become important tools for finding genomic regions of interest in breeding programs, due to the fact that their improved more accuracy than the other tools. The aim of this work was to map genomic regions associated with grain maturation in common maize strains.

For linkage disequilibrium mapping, 72 strains were previously genotyped for SNP markers on the 650K platform and their respective genotypic values were predicted for male and female flowering and area below the moisture curve. The analysis of association between the SNPs markers and the characters was performed using mixed linear model and stepwise multiple regression.

The significant associations detected for male and female flowering were found to be distributed in all chromosomes, with a higher concentration in genomic regions of chromosomes 1, 2, 3, 5, 9 and 10. For the area below the moisture curve, it was found a smaller number of significant associations, being concentrated in the chromosomes 1, 2, 3, 6, 9 and 10 and absent in chromosomes 4 and 8. By stepwise analysis, it obtained complete models that account for 79, 93 and 56% of the variation for the genotypic values, respectively, with the identification of genomic regions pre-dominantly on chromosomes 1 and 3.

Thus, the detection of similar and distinct genomic regions for these traits, reveals the potential for the use of significant associations detected in chromosomes 1 and 3 to obtain the germplasm maturity required in breeding programs.