Co-overexpression of RCA and AVP1 in cotton substantially improves fiber yield for cotton under drought, moderate heat, and salt stress conditions

Abiotic stresses such as drought, heat, and salt are major causes of crop failure and are the main challenges that we face in agriculture. Genetic engineering has been successful in controlling harmful insects and conferring herbicide resistance, but has yet to produce similar results in reducing damages caused by abiotic stresses. It was previously shown that overexpression of AVP1 that encodes a vascular H+-pyrophosphatase in Arabidopsis could increase drought and salt tolerance and overexpression of RCA that encodes Rubisco activase in Larrea tridentata could increase heat tolerance in transgenic plants. It was therefore hypothesized that cooverexpression of AVP1 and RCA would make transgenic plants more tolerant to all three stresses simultaneously. Indeed, this hypothesis was confirmed in Arabidopsis. To test if this result could be duplicated in an actual crop, AVP1 and RCA were co-overexpressed in cotton. The results from this study indicated that RCA/AVP1 co-overexpressing cotton plants produced 50% and 96% higher seed fiber yield than wild-type cotton under combined drought and salt stresses and combined drought and heat stresses, respectively. Furthermore, RCA/AVP1 co-overexpressing cotton plants showed a 6.5-fold increase in net photosynthetic rates under heat stress as well as having much higher Vcmax rates under multiple stress conditions. Results from two field studies showed that RCA/AVP1 co-overexpressing cotton plants had 90% and 66-75% increase in seed fiber yield in comparing to wild-type cotton under dryland conditions. This study proves that cooverexpression of AVP1 and RCA can improve cotton's fiber yield in a dryland agricultural region, and this approach could increase other crops' yield in arid and semiarid regions of the world.