Alelos asociados al índice de severidad de la enfermedad mal de Río Cuarto en germoplasma exótico de maíz

Abstract

Mal de Río Cuarto (MRC) is one of the most important viral diseases of maize in Argentina.The disease severity index (DSI) allows to combine the incidence and severity of a disease ina single metric. The genotypic reaction to MRC has been extensively studied in biparentalpopulations. However, this complex trait has not been analyzed by genome-wide associationstudies (GWAS). The aim of this work is to identify new resistance alleles associated withDSI of MRC in an exotic germplasm from the International Maize and Wheat ImprovementCenter (CIMMYT). A population of maize lines from CIMMYT was phenotypicallyevaluated in environments in the area where the disease is endemic. The predictors ofgenetic effects (BLUP, best linear unbiased predictor) and 78,376 SNP markers (SingleNucleotide Polymorphism) were used to perform the GWAS in 186 maize lines. The valuesof variance components and mean-basis heritability suggest a wide genotypic variabilityin the population. The GWAS allowed to identify 11 putative QTL of resistance to MRC. Theincorporation of exotic germplasm into local maize breeding programs could contributefavorably to the creation of hybrids with a higher level of resistance to MRC. The predictiveability of associated markers with MRC resistance indicates that marker-assisted selectionis an advisable tool for selecting MRC resistant genotypes.