To identify and transfer stress tolerance related genes from tepary bean to common bean, leading to the development of common bean varieties with improved abiotic stress (drought, heat and cold) tolerance.
Tepary bean (Phaseolus acutifolius Gray), a relative of common bean has been reported to be tolerant to abiotic stresses including drought, cold and heat. Our preliminary screening of wild tepary accessions for tolerance to sub-zero temperatures demonstrated that the wild tepary bean accession, W6 15578 is a potential donor of tolerance to cold. We had already developed an interspecific backcross introgression population from a cross between common bean (NY5-161) and W6 15578 with a view to improve stress tolerance. We hypothesized that there is possibility of selecting for germplasm tolerant to sub-zero temperatures by screening for drought hence the population was evaluated under sub-zero (Saskatoon) and water stress (Puerto Rico) conditions. A few lines were found to be superior to the common bean parent under both stress conditions.
Tepary bean and introgression lines were genotyped using our existing tepary and common bean GoldenGate SNP arrays using published methods. A map of the tepary bean genome was developed and compared to that of common bean genome. Differences are restricted to intra-chromosomal rearrangements. Introgression of tepary bean DNA could be tracked in the interspecific introgression lines and some regions could be associated with traits of interest.
Agronomic evaluation of introgression lines in Saskatoon was carried out and a subset of selected introgression lines selected to be grown in three locations (MB, SK & AB). Results suggest that the introgression line C-11-2 is a stable and a better performer than the common bean checks across locations. Based on yield, days to maturity and cold tolerance, two promising entries (C-11-2 and B-11-3) were used in further backcrosses with promising SK-adapted tepary bean lines and pinto beans. These backcrosses and the introgression lines could be used to improve abiotic stress tolerance in common bean. Thus interspecific introgression of portions of the tepary bean genome into common bean is a promising approach for increasing abiotic stress tolerance in common bean.