Heterologous Expression of Rice SUMO E3 Ligase (OsSIZ1) Enhances Drought and Heat Tolerance in Transgenic Cotton

The Arabidopsis gene AtSIZ1 encodes a SUMO E3 ligase that plays important roles in plant response to abiotic stresses such as drought, heat, cold, salt, and nutrient starvation. Loss of function in AtSIZ1 leads to increased sensitivity to drought, heat, and salt stresses, whereas overexpression of the rice OsSIZ1, a homolog of AtSIZ1, in bentgrass leads to increased heat and drought tolerance. To test if overexpression of OsSIZ1 in cotton could increase cotton's tolerance to various stresses, we generated transgenic cotton plants containing the OsSIZ1 gene. We analyzed the performance of OsSIZ1-transgenic cotton under drought and heat stress conditions, and our preliminary results show that transgenic cotton plants perform significantly better than wild-type cotton plants in photosynthesis, water use efficiency, as well as in fiber yield under heat and drought conditions. Since drought and heat are the major limiting factors for cotton production in Texas High Plains, we expect that OsSIZ1-transgenic cotton plants will out-perform non-transgenic cotton in the field conditions of Texas High Plains.