Identificação de região genômica associada à resistência do feijão-comum à Pseudocercospora griseola em condições de campo

Abstract

Common bean (Phaseolus vulgaris L.) is one of the most important crops for global food secu- rity, especially in developing countries, where it is of the main sources of vegetable protein. Angular leaf spot, caused by the fungus Pseudocercospora griseola, is one of the major diseases affecting this crop, leading to significant losses. The use of resistant cultivars is a primary strat- egy for disease control, reducing significantly crop production losses. An example of this is the development of the MAIII-16.159 line, resistant to P. griseola isolates, through a partnership between the Plant Genetics and Breeding Program at the Universidade Federal of Lavras and EMBRAPA in Brazil. The identification of genes involved in resistance is important to better understand the plant's defense mechanisms and interaction between pathogen and host, which makes it possible to identify and understand the genes involved in this defense response. There- fore, the objective of this study was to identify genomic regions associated with resistance to P. griseola. For this, we used inbred lines obtained from a biparental cross of pure and con- trasting parents for resistance to P. griseola. The study panel to identify resistance to Angular Spot was composed of 180 inbred lines derived from the cross between MAIII-16.159 (re- sistant) and BRS Horizonte (susceptible), which presented a significant deviation in the segre- gation proportion. The lines were subjected to phenotyping and genotyping to identify molec- ular markers. The phenotypic assessment of the severity of the angular spot of the strains was carried out in the field at the R8 stage, conducted in DBC with two replications, under natural conditions of occurrence of the pathogen during the 2022/2023 water harvest. This physiolog- ical stage represents the point of maturation of the pods, indicating the period in which they fill. Genotyping was carried out using SNPs (Single Nucleotide Polymorphisms) and silico-DArT (Diversity Arrays Technology) markers. Genes were identified using v2.1 of the common bean genomic sequence in Phytozome v1.16.9. A significant marker was identified, the DART3819 marker, located at position 14,329,208 bp of the PV04 chromosome. This marker revealed a statistically significant association with resistance to angular spot, presenting a negative effect (-0.92) that contributed to reducing the severity of the disease, explaining 47% of the observed phenotypic variation. Therefore, the MAIII-16.159 line possesses a region on chromosome Pv04 associated with gene alleles responsible for resistance to P. griseola at stage R8 of com- mon bean development.