TaSnRK2.9, a Sucrose Non-fermenting 1-Related Protein Kinase Gene, Positively Regulates Plant Response to Drought and Salt Stress in Transgenic Tobacco

Abstract

Sucrose non-fermenting 1-related protein kinase 2 (SnRK2) family members play crucial roles in plant abiotic stress response. However, the precise mechanism underlying the function of SnRKs has not been thoroughly elucidated in plants. In this research, a novel <i>SnRK2</i> gene, <i>TaSnRK2.9</i> was cloned and characterized from common wheat. The expression of <i>TaSnRK2.9</i> was upregulated by polyethylene glycol (PEG), NaCl, H₂O₂, abscisic acid (ABA), methyl jasmonate (MeJA), and ethrel treatments. <i>TaSnRK2.9</i> was mainly expressed in wheat young root, stamen, pistil, and lemma. Overexpressing <i>TaSnRK2.9</i> in transgenic tobacco enhanced plants' tolerance to drought and salt stresses both in young seedlings and mature plants with improved survival rate, seed germination rate, and root length. Physiological analyses suggest that TaSnRK2.9 improved antioxidant system such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione (GSH) to reduce the H₂O₂ content under drought or salt stress. Additionally, <i>TaSnRK2.9</i> overexpression plants had elevated ABA content, implying that the function of TaSnRK2.9 may be ABA-dependent. Moreover, TaSnRK2.9 increased the expression of some ROS-related, ABA-related, and stress-response genes under osmotic or salt treatment. TaSnRK2.9 could interact with NtABF2 in yeast two-hybrid assay, and increased the expression of <i>NtABF2</i> under mannitol or NaCl treatment in transgenic tobacco plants. In conclusion, overexpression of <i>TaSnRK2.9</i> in tobacco conferred plants tolerance to drought and salt stresses through enhanced ROS scavenging ability, ABA-dependent signal transduction, and specific SnRK-ABF interaction.