Mississippi State University Starkville, Mississippi
Body of Abstract: Cowpea (Vigna unguiculata) is a vital legume crop grown in semi-arid regions, where drought stress severely affects its productivity. To understand how cowpea responds to drought stress, this study utilized proteomics analysis. Leaf samples were collected for proteomics analysis from three cowpea genotypes, namely Arkansas Blackeye (ARB), X17-111, and Top Pick Cream (TPC), which exhibit varying levels of drought tolerance. These genotypes were exposed to drought stress under different volumetric water content (VWC) treatments.
In response to drought stress, a total of 1,085 differentially abundant proteins (DAPs) were identified. Each genotype exhibited unique DAPs, with 154 in ARB, 170 in X17-111, and 242 in TPC. Across the three VWC treatments, 601 unique DAPs were identified, including 175 proteins in the drought-stressed treatment, 281 in the intermediate treatment, and 145 in the well-watered treatment. Functional annotation of the DAPs revealed their involvement in processes such as photosynthesis, oxidative stress, and carbohydrate metabolism.
The drought-tolerant genotype showed higher abundance of stress response proteins, including chaperones, lyases, hydrolases, antioxidant enzymes, as well as proteins related to osmotic adjustment and carbon fixation, compared to the other genotypes. Analysis of functional pathways highlighted significant changes in the ribosome pathway across most genotype comparisons, suggesting the importance of translation regulation in drought-resistant cowpea varieties. Notably, the ARB genotype exhibited downregulated DAPs under metabolic pathways during drought stress, while the TPC and X17-111 genotypes showed upregulated DAPs. The X17-111 and ARB genotypes had downregulated DAPs under the spliceosome pathway.
These findings suggest that the regulation of protein abundance involved in photosynthetic and proteosome pathways is crucial for cowpea's response to drought stress. The identified proteins offer valuable insights into the molecular mechanisms underlying drought tolerance in cowpea and can serve as potential targets for genetic improvement of drought resistance in this important crop.