Expression of candidate genes related to white mold resistance in common beans

Abstract

White mold caused by Sclerotinia sclerotiorum is an important disease that may lead to severe crop losses. The resistance of common bean (Phaseolus vulgaris) to white mold is quantitative and affected by environmental conditions. In this case, QTL identification of higher effect and stable in several populations and environments (Meta-QTL) can be useful in marker-assisted breeding. This study aimed to analyze the expression of candidate genes within Meta-QTL regions in two common bean lines Cornell 605 (resistant) and Beryl (susceptible), inoculated with S. sclerotiorum, at different evaluation times. We did so by conducting a phenotypic analysis of the reaction lines were evaluated at 3, 7 and 11 days after inoculation (DAI), with the aim of verifying the reaction discrepancy between the lines in the test environment, and assessing the the expressions of seven genes (PvPKF, PvF-Box, PvERF1, PvPGIP4, PvPR1, PvPOD and PvMYB) within Meta-QTL intervals were analyzed in the lines, at 0, 24, 48 and 72 h after inoculation (HAI). The phenotypic evaluation showed high susceptibility in Beryl and suggested that most of the interaction between lines and evaluation times occurred due to the rapid development of symptoms in the susceptible line. Based on RT-qPCR results, the genes PvPKF and PvPOD were the most promising to explain partial Cornell 605 resistance conditioning. Differences in the genetic backgrounds of the lines used in this study and the fact that the evaluations were performed in a greenhouse may help to explain why the other candidate genes were not highly expressed in Cornell 605.