Genetic architecture of root-knot nematode resistance in common beans

• Ano de defesa: 2023
• Autor(a) principal: Souza, Talissa de Oliveira Floriani Zimmermann de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Meloidogyne incognita; Phaseolus vulgaris L.; Candidate genes; Genes candidatos; Mapeamento de QTLs; QTL mapping
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11137/tde-04012024-170539/

The common bean (Phaseolus vulgaris L.) is a crop used for direct human consumption. The grain covers essential micronutrients and valuable protein content, thus contributing to food security in developing countries. However, attacks by root-knot nematode (RKN - Meloidogyne incognita) threaten common bean cultivation, causing substantial yield losses. Undoubtedly, crop resistance is an outstanding approach for suppressing nematode infection. To give continuity to our previous studies for unveiling the genetic architecture of typical bean response to RKN (race 3 of Meloidogyne incognita), contrasting genotypes were identified and crossed. The segregating population (F2), which consisted of 388 individuals, was genotyped using GBS (genotyping-by-sequencing), and a customized high-throughput phenotyping approach was developed to acquire trait data for a subset of 200 F2:3 families. The traits egg mass (EM), root-galling index (RG), and root dry mass (RM) were evaluated over time within greenhouse conditions under a completely randomized design with ten replicates. Linkage and quantitative trait loci (QTL) mapping were carried out, and functional mapping of the associated regions was used for candidate genes discovery. A total Linkage map resulting in 954 SNPs assigned to 11 linkage groups totaling 1,687 cM was used as a basis for Composite Interval Mapping (CIM) and Multiple Interval Mapping (MIM), identifying four major QTLs (Pv03, Pv05, Pv08 and Pv10). The selected model was used to calculate the genotypic values of individuals, with the marker-assisted selection (MAS) approach, arriving at a list of the top 10 genotypes for use in MAS. The correlation between observed and predicted values was 0.72, considered high; the result shows the relevance of the model. Candidate genes were identified in response to GI, with domains related to WRKY and MAPK (Mitogen-Activated Protein Kinase) cascades. This work represents a significant step in understanding the genetic architecture of RNK resistance in the common bean. It sets the stage for implementing MAS in a breeding population against pathogen resistance in the bean family.