Drought-Induced Increase In Catalase Activity Improves Cotton Yield When Grown Under Water-Limiting Field Conditions

Plants experiencing abiotic stress can produce excessive reactive oxygen species (ROS), ultimately impacting the crop growth and yield. Hydrogen peroxide H2O2 is a relatively stable active ROS and is mainly scavenged by catalase. In this study, the catalase-encoding E. coli KatE gene was transferred to cotton plants by Agrobacterium-mediated transformation. From almost 100 independent transgenic lines, three transgenic lines were identified that did not display a discernible growth and yield phenotype when grown under well-watered field conditions, but were tolerant to drought under field conditions, resulting in a similar to 25% higher cotton-seed yield. The three lines were analysed under controlled laboratory conditions to explain the drought-dependent phenotype: the transgenic lines displayed drought-inducible EcKatE expression and total catalase activity was only higher than that of the wild type during growth under drought or salinity stress. Furthermore, drought-induced ectopic EcKatE expression increased total SOD and POD activities, decreased H2O2 levels and improved photosystem II performance and relative water content. The results show that ectopic EcKatE expression displays an advantage during drought stress, without negatively affecting yield during well-watered field conditions. EcKatE overexpression confers hyper-resistance to drought in cotton and provides improved cotton-seed yield under water-limiting field conditions. And the EcKatE gene might also be a promising drought-resistant gene for improving other crop varieties.