A Tritipyrum-Derived HVA22 Homolog Enhances Wheat Salt Tolerance

HVA22 is a gene induced by abscisic acid (ABA) and abiotic stress. Previous transcriptome data of salt-tolerant Tritipyrum “Y1805” revealed that HVA22 was significantly upregulated under salt stress. Gene TtHVA22 was successfully amplified from “Y1805”, with an open reading frame of 468 bp and encoding a protein of 156 amino acids. Gene TtHVA22 was transformed into bread wheat “1718” via coleoptile method. The relative expression level of TtHVA22 in roots was remarkably higher than in stems and leaves under salt stress. During the seedling stage, the TtHVA22 overexpression (OE) line exhibited less leaf wilting under salt stress than wild-type (WT) plants. Under salt stress and recovery conditions, TtHVA22 OE significantly increased root length, plant height, fresh weight, and dry weight compared to WT plants. Additionally, the levels of ABA, soluble sugars, soluble proteins, proline, pyruvate, and photosynthetic pigments and peroxidase activity were significantly higher in the OE lines than in the WT plants; however, their malondialdehyde content and relative conductivity were opposite. Two years of field data demonstrated that stem diameter and grain yield per plant were significantly greater in the OE lines than the WT plants. Therefore, wheat salt tolerance was improved in the TtHVA22 OE lines by osmotic regulation, antioxidation, and chlorophyll stabilization.