An integrative analysis of yield stability for a GWAS in a small soybean breeding population.

Drought stress is one of the most important factors limiting soybean [Glycine max (L.) Merr.] productivity and reducing yield stability. Soybean breeders need phenotypic and genotypic tools to improve drought stress tolerance, but most of available strategies are expensive and unaffordable for small‐scale public breeding programs. In this study, elite germplasm of a locally adapted breeding population was used to estimate a yield stability index as an indicator of drought response. In order to associate yield stability of analyzed genotypes to drought response, water deficit scenarios related to the crop cycle group were defined. Four groups of genotypes were identified in relation to yield stability: two groups showed stables yield (without interaction with water deficit scenarios), and two groups showed unstable yield (with crossover interaction with water deficit scenarios). This phenotypic information was used to identify genomic regions and candidate genes associated with yield stability index. A new method for the definition of a quantitative trait loci (QTL) region was developed based on the probability of marker pairwise of belonging to four linkage disequilibrium (LD) categories. Seven QTL were found and their implication on drought tolerance was further supported by linkage to previously reported QTL for water use efficiency trait. [ABSTRACT FROM AUTHOR]