Drought Response in the Transcriptome and Ionome of Wild and Domesticated Lablab purpureus L. Sweet, an Underutilized Legume

Hunger remains a prevalent issue worldwide, and with a changing climate, it is expected to become an even greater problem that our food systems are not adapted to. There is therefore a need to investigate strategies to fortify our foods and food systems. Underutilized crops are farmed regionally, are often adapted to stresses, including droughts, and have great nutritional profiles, potentially being key for food security. One of these crops, Lablab purpureus L Sweet, or lablab, is a legume grown for humans or as fodder and shows remarkable drought tolerance. Understanding of lablab's molecular responses to drought and drought's effects on its nutritional qualities is limited and affects breeding potential. Using transcriptomics at three time points, changes in gene expression in response to drought were investigated in wild and domesticated lablab. The effect of drought on the elemental profile of lablab leaves was investigated using ionomics to assess drought's impact on nutritional quality. Differences in drought response between wild and domesticated lablab accessions were revealed, which were mainly due to differences in the expression of genes related to phosphorus metabolic response, cell wall organization, and cellular signaling. The leaves of wild and domesticated lablab accessions differed significantly in their elemental concentrations, with wild accessions having higher protein, zinc, and iron concentrations. Drought affected the concentration of some elements, with potential implications for the use of lablab under different environments. Overall, this study is an important first step in understanding drought response in lablab with implications for breeding and improvement of drought-tolerant lablab.