Over-expression of rice SUMO E3 ligase gene OsSIZ1 in cotton enhances both drought and heat tolerance



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The Arabidopsis SUMO E3 ligase gene AtSIZ1 plays important roles in plant response to abiotic stresses as loss of function in AtSIZ1 leads to increased sensitivity to drought, heat, and salt stresses. Overexpression of AtSIZ1’s homolog, OsSIZ1, in bentgrass leads to increased heat and drought tolerance, indicating that the function of the E3 ligase SIZ1 is highly conserved in plants. To test the possibility that the SUMO E3 ligase could be used to engineer drought- and heat-tolerant crops, the rice gene OsSIZ1 was overexpressed in cotton. Analyses of OsSIZ1-transgenic cotton plants indicate that OsSIZ1-overexpression in cotton substantially increased heat-tolerance and drought-tolerance in growth chamber and greenhouse conditions, by displaying significantly higher photosynthetic rates and higher fiber yields under water deficit and heat conditions. More importantly, under the condition of combined heat stress and reduced irrigation, OsSIZ1-transgenic cotton plants showed at least 36% higher photosynthetic rates and 36% higher yields than wild-type and segregated non-transgenic plants. Furthermore, in field trials, OsSIZ1-transgenic cotton plants produced 32% higher yields under reduced irrigation condition in 2014 and 20% higher yields under rainfed condition in 2015, indicating a great potential for the use of OsSIZ1 to improve crop yields under water limited and dryland agricultural production systems.



SUMO E3 Ligase, Drought Stress, Heat Stress, Sumoylation, Transgenic Cotton