Expression of Arabidopsis HOMEODOMAIN GLABROUS 11 Enhances Tolerance to Drought Stress in Transgenic Sweet Potato Plants

Sweet potato (Ipomoea batatas L. cv. Lizixiang) is a nutritious arable crop with a low drought tolerance during growth and maturation. The Arabidopsis HOMEODOMAIN GLABROUS 11 (HDG11) gene can increase drought tolerance in tobacco and tall fescue plants. To determine the effect of HDG11 in the sweet potato, transgenic plants that expressed the HDG11 gene were generated by Agrobacterium-mediated transformation. Expression of the transgene was confirmed using Southern blotting, reverse transcription-polymerase chain reaction (RT-PCR) and DNA sequencing. Two independent HDG11 transgenic lines were evaluated and increased drought stress tolerance was observed in both lines, compared to wild-type (WT) plants. Under drought stress conditions, net photosynthesis rate (Pn), the efficiency of excitation energy captured by open PSII reaction centers (Fv/Fm) and water use efficiency (WUE) increased, and transpiration rate (Tr) decreased in HDG11 transgenic plants compared to WT. HDG11 transgenic plants also had decreased lipid membrane oxidative damage, reduced H2O2 accumulation and increased ROS-scavenging enzyme activity during drought stress treatment. This study indicates that overexpression of the Arabidopsis HDG11 gene improved drought tolerance in the sweet potato.