Cotton Plants Co-Overexpressing AVP1 and OsSIZ1 Show Improved Phenotype and Increased Yield Under Multiple-Stress Conditions

Abiotic stresses such as extreme temperatures, soil water deficit, and salinity negatively affect plant growth and development and cause significant yield loss. We previously showed that overexpression of the Arabidopsis vacuolar proton pyrophosphatase gene AVP1 in cotton increased fiber yield when plants were exposed to salt and drought stresses. Additionally, we have recently shown that overexpression of the rice SUMO E3 ligase gene OsSIZ1 in cotton led to higher fiber yield under drought and heat conditions. In this study, we co-overexpressed AVP1 and SIZ1 to test for possible synergistic effects that could result from increased activity of these genes. We found that AVP1/OsSIZ1 plants performed significantly better under drought, salt, combined heat and drought, and combined salt and drought conditions, and produced higher fiber yields than the single gene overexpressing plants and wild-type plants. Our results suggest that co-overexpression of AVP1 and SIZ1 is a viable strategy for engineering abiotic stress tolerance and improving cotton yields in low input or marginal environments.