Mapeamento de QTLs associados à resistência do trigo à giberela e a níveis de produção de deoxynivalenol, por desequilíbrio de ligação

Abstract

Fusarium head blight is one of the main diseases that affects the wheat crop, causing losses of productivity, besides making possible the production of deoxynivalenol mycotoxin, highly harmful to the individuals that ingest it. The marker assisted selection can help these programs to reduce time and costs in development of new cultivars resistant to Fusarium head blight, but for a better efficience, is required knowing the location of genes or QTLs associated to the trait. The objective of this research was to identify SNPs associated to genes/QTLs of resistance to Fusarium head blight and deoxynivalenol production in a wheat cultivars group, for use in MAS on wheat genetic breeding. Were used 384 cultivars to evaluate the Fusarium head blight resistance. Genotyping was using the chip with 35,000 SNPs markers. The population structure was estimate by the algorithm Marcov Chain Monte Carlo for the generalised Bayesian clustering method. The association analysis was performing using the Mixed Linear models method, with 0.001% of significance level, and, stepwise multiple regression, besides an analysis of Pearson‟s correlation. The results showed that the resistance of brazilian wheat genotypes to Fusarium head blight is not related to the QTLs on chromosome 3B, often associated to the Fhb1 gene, but to the QTLs present on chromosomes 1B, 4D and 7D whose explained 13.6% of phenotypic variation. The DON mycotoxin analysis identified nine significant SNPs associated to QTLs on chromosomes 1A, 1B, 1D, 2D, 3D, 5D, 6D and 7B with 65.7% of phenotypic explanation to deoxynivalenol production. In addition, both correlation and association analysis suggest distinct genetic control acting to determine the characteristics.