Adaptation of winged bean (Psophocarpus tetragonolobus (L.) DC.) to drought stress is mediated by root-tuber heat-shock proteins and specific metabolites

Abstract

Winged bean (Psophocarpus tetragonolobus (L.) DC.) is an underexploited tropical legume whose tuberous-roots have 12–19% proteins. The species has excellent drought tolerance ability thus making it a prospective climate-smart future crop. However, the underlying defense mechanism(s) of the species against the drought stress are not yet understood. Therefore, we studied the role of root- tuber proteins and metabolites in providing drought stress resistance to winged bean. We identified and characterized the relevant proteins and their corresponding peptides, and validated the responsible transcripts in root-tubers of P. tetragonolobus through qRT-PCR. Total proteome-analysis of root-tubers resulted in identification of 2678 proteins belonging to 154 families. Of these, 96% of proteins are associated with known biological activities. Heat-shock proteins (Hsps) of 12–42 kDa were the most abundant protein families and constituted 13% of the total identified proteins in the root-tuber. Metabolite analysis of the root-tuber revealed the prevalence of abiotic stress tolerant amino acids and compounds such as dimethyl amide, hydroxylamine hydrochloride, trimethylamine, cyclopropylamine, α-aminopropionitrile and cyclohexylamine. The other related metabolites present were naphthalene, benzyl alcohol, L- rhamnose, propanol and aromatic aldehydes. The presence of several Hsps, aminoacids, and specific metabolites with known function of stress-amelioration/anti-oxidant activities present in the root-tubers explains the adaptation success of winged bean against drought stress.