Interspecific common bean population derived from Phaseolus acutifolius using a bridging genotype demonstrate useful adaptation to heat tolerance

Abstract

Common bean (Phaseolus vulgaris L.) is an important legume crop worldwide and is a major nutrient source in the tropics. Common bean reproductive development is strongly affected by heat stress, particularly overnight temperatures above 20°C. The desert Tepary bean (Phaseolus acutifolius A. Gray) offers a promising source of adaptative genes due to its natural acclimation to arid conditions. Hybridization between both species is challenging, requiring in vitro embryo rescue and multiple backcrossing cycles to restore fertility. This labor-intensive process constrains developing mapping populations necessary for studying heat tolerance. Here we show the development of an interspecific mapping population using a novel technique based on a bridging genotype derived from P. vulgaris, P. Acutifolius and P. parvifolius named VAP1 and is compatible with both common and tepary bean. The population was based on two wild P. acutifolius accessions, repeatedly crossed with Mesoamerican elite common bush bean breeding lines. The population was genotyped through genotyping-by-sequencing and evaluated for heat tolerance by genome-wide association studies. We found that the population harbored 59.8% introgressions from wild tepary, but also genetic regions from Phaseolus parvifolius, a relative represented in some early bridging crosses. We found 27 significative quantitative trait loci, nine located inside tepary introgressed segments exhibiting allelic effects that reduced seed weight, and increased the number of empty pods, seeds per pod, stem production and yield under high temperature conditions. Our results demonstrate that the bridging genotype VAP1 can intercross common bean with tepary bean and positively influence the physiology of derived interspecific lines, which displayed useful variance for heat tolerance.

Genetic differentiation of a southern Africa tepary bean (Phaseolus acutifolius A Gray) germplasm collection using high-density DArTseq SNP markers

“…The grains are a source of proteins, lipids and essential mineral elements [3]. The crop is tolerant to drought and heat stress [1,4,5], allowing its cultivation in dry environments. It is highly resistant to diseases including bacterial blight [Xanthomonas campestris pv.…”

“…DArTseq SNP markers have been used for quantitative trait loci (QTL) mapping, genome-wide association studies, the development of linkage maps, genetic diversity, and population structure analyses in several legume crops, including pigeonpea, chickpea, soybean, and common bean [30][31][32][33][34]. Genetic diversity and population structures were examined in Interspecific Mesoamerican X Wild Tepary (IMAWT) population using GBS with high-density SNP markers aligned to the common bean reference genome [5]. Further, GBS with highdensity SNP markers mapped to the tepary bean reference genome in a tepary bean diversity panel has been used to determine the extent of genetic diversity and population structure [35].…”