Identification of common bean resistance sources against the phytopathogen Sclerotinia sclerotiorum
Phaseolus vulgaris; Sclerotinia sclerotiorum (Lib.) de Bary; Straw test; Seedling straw test.
Common beans (Phaseolus vulgaris L.) are of great importance in the global diet due to their low cost and nutritional quality. Several factors limit the production of the crop, especially the disease called white mold, caused by the phytopathogen Sclerotinia sclerotiorum (Lib.) De Bary. Among the most suitable control methods, which offer greater savings and less risk to the environment, is the use of resistant cultivars, through genetic resistance. Thus, this study aimed to identify sources of resistance to white mold among common bean cultivars of Andean and Mesoamerican origin. The experiment was carried out in a greenhouse and in a laboratory in a Randomized Block Design (DBC) with six replications and two inoculation methods, the straw test straw inoculation method, with 109 genotypes. The experiment was carried out at the State University of Mato Grosso, Cáceres and at the Laboratory of Genetic Resources and Biotechnology also in Caceres, Mato Grosso, between the months of March and May 2019. It was used by UFV-Ss493, grown in BDA (Potato Dextrose Agar) poured into 90 x 30 mm Petri dishes, stored in the BOD chamber (Bioclimatic Oxygen Demand) with a temperature of 23 ° C and a photoperiod of 12 hours. The inoculation method can consist of inoculated plants 21 to 28 days after planting, cutting with sterile scalpel at the point of growth of the plant below the second well-developed trefoil. While the seedling test uses plants for 15-day inoculation, cutting with a sterilized scalpel at the point of growth of the main stem of the plant below the first trefoil and displaying a mycelium disk followed by the protection of a 200 ul bridge. Variables of lesion length and scores were observed every two days. There was a significant difference in all variables, such as the cannula inoculation method and the cannula inoculation method. The genotypes BGF 205, BGF 203, BGF 200 and BGF 67 were considered the most resident when compared to the other bean materials used in this work. Therefore, these genotypes can be considered as a source of resistance to the pathogen that causes white mold in the improvement protocols of common beans.