Towards Doubling Fibre Yield For Cotton In The Semiarid Agricultural Area By Increasing Tolerance To Drought, Heat And Salinity Simultaneously

Abiotic stresses such as extreme temperatures, water-deficit and salinity negatively affect plant growth and development, and cause significant yield losses. It was previously shown that co-overexpression of the Arabidopsis vacuolar pyrophosphatase geneAVP1and the rice SUMO E3 ligase geneOsSIZ1in Arabidopsis significantly increased tolerance to multiple abiotic stresses and led to increased seed yield for plants grown under single or multiple abiotic stress conditions. It was hypothesized that there might be synergistic effects betweenAVP1overexpression andOsSIZ1overexpression, which could lead to substantially increased yields if these two genes are co-overexpressed in real crops. To test this hypothesis,AVP1andOsSIZ1were co-overexpressed in cotton, and the impact ofOsSIZ1/AVP1co-overexpression on cotton's performance under normal growth and multiple stress conditions were analysed. It was found thatOsSIZ1/AVP1co-overexpressing plants performed significantly better thanAVP1-overexpressing,OsSIZ1-overexpressing and wild-type cotton plants under single, as well as under multiple stress conditions in laboratory and field conditions. Two field studies showed thatOsSIZ1/AVP1co-overexpressing plants produced 133% and 81% more fibre than wild-type cotton in the dryland conditions of West Texas. This research illustrates that co-overexpression ofAVP1andOsSIZ1is a viable strategy for engineering abiotic stress-tolerant crops and could substantially improve crop yields in low input or marginal environments, providing a solution for food security for countries in arid and semiarid regions of the world.