Overexpression of A Biotic Stress-Inducible Gene Activates Early Protective Responses in Tobacco under Combined Heat and Drought.

Drought and heat stresses are major factors limiting crop growth and productivity, and their effect is more devastating when occurring concurrently. Plant glutathione transferases (GSTs) are differentially expressed in response to different stimuli, conferring tolerance to a wide range of abiotic stresses. GSTs from drought-tolerant var. "Plake Megalosperma Prespon" is expected to play an important role in the response mechanisms to combined and single heat and drought stresses. Herein, we examined wild-type plants (cv. Basmas Xanthi) and T1 transgenic lines overexpressing the stress-induced and genes. The overexpression of contributed to potential thermotolerance and greater plant performance under combined stress. Significant alterations in the primary metabolism were observed in the transgenic plants between combined stress and stress-free conditions. Stress-responsive differentially expressed genes (DEGs) and transcription factors (TFs) related to photosynthesis, signal transduction, starch and sucrose metabolism, osmotic adjustment and thermotolerance, were identified under combined stress. In contrast, induction of certain DEGs and TF families under stress-free conditions indicated that transgenic plants were in a primed state. The overexpression of the is playing a leading role in the production of signaling molecules, induction of specific metabolites and activation of the protective mechanisms for enhanced protection against combined abiotic stresses in tobacco.