Expressão de genes candidatos do feijão relacionados à resistência ao mofo branco e comparação de métodos de fenotipagem da reação ao patógeno

Abstract

Prospecting bean genotypes resistant to white mold (Sclerotinia sclerotiorum (Lib.) de Bary) have been a priority for cheap and efficient control of this important pathogen. In this mission, several tools can be integrated to improve selection efficiency, and thus increase the genetic gain in breeding programs that have sought genotypes resistant to this pathogen. The mapping and validation of resistance genes are of direct interest in assisted selection in breeding programs, whereas accurate and efficient phenotyping methods are important throughout the breeding program, from germplasm screening to the advanced breeding generations. The objectives of this dissertation were: (i) to analyze the expression of genes located within Meta-QTLs in contrasting lines in terms of resistance to S. sclerotiorum; and (ii) to compare the straw and seedling test phenotyping methods, using aspects of the disease progression through nonlinear models, as well as to evaluate the interaction of the phenotyping method with the level of resistance of the genotypes and the evaluation period. In the first work, high susceptibility was observed for the Beryl line in the phenotypic evaluation, and that a large part of the interaction between lines and evaluation period occurred due to the rapid growth of symptoms in this line from the third day after inoculation. Of the genes evaluated for transcription expression, the PvPKF and PvPOD genes were the most promising in relation to the resistance of the Cornell 605 line. Differences in the genetic background of the populations and the fact that the evaluation was done in a greenhouse could explain the fact that there was not a necessarily greater expression of the candidate genes in the Cornell 605 line. The results of the second work demonstrated that the two different phenotyping methods are well correlated within the bean resistance groups, however, they make distinct inferences about the resistance of the beans genotypes, and the progress of the disease is closely related to the resistance level of the evaluated genotype. The two methods of phenotyping are efficient, but in different situations, as well as the progress models of the symptoms tested have adjustment similar to the levels of symptoms observed in both methods.