Elucidation of drought tolerance potential of horsegram (Macrotyloma uniflorum Var.) germplasm using genome wide association studies.

Horsegram [Macrotyloma uniflorum Lam (Verdc.)] is an undervalued and under studied legume though is a good source of proteins, carbohydrates and energy. Drought is an abiotic stress that effects plant development and ecosystem sustainability. Drought is expected to become more common in the future as a result of climate change. Horsegram is known to withstand drought, salt and heavy metal stress. In the past few decades application of genome-wide association studies (GWAS) to explore complex traits has risen in popularity. Considering the above mentioned factors drought tolerance ability of horsegram germplasm was investigated in 96 diverse horsegram lines with GWAS by exploring 20241 SNPs. Highest number of SNPs were found to be located in intergenic regions (43.8%) followed by intronic SNPs (21.6%). In this investigation three drought tolerant representing parameters were selected for QTL identification. In the present study, we identified different SNPs associated with QTLs governing these traits, which involved in drought stress response of horsegram plant. Seven QTLs were found to be associated with relative water content in horsegram whereas for root volume and root length 4 and 8 QTLs were found respectively. By using horsegram database of Kazusa DNA research institute Japan, we identify the genes present on these marker sites which were found to be involved in many biochemical pathways related to plant abiotic stresses. Many of these genes were previously characterized and few uncharacterized genes were also found controlling these traits. These findings will help in identifying new mechanisms responsible for plant drought stress tolerance in future.