Genome-wide identification of the aminotransferase gene family in wheat and functional characterization of the TaOBF1B-TaNAAT1 module in salt tolerance.

Abstract

Soil salinization is a major abiotic stress limiting global wheat production. The Aminotransferase (AT) superfamily plays vital roles in plant metabolism and stress responses; however, a comprehensive analysis of this family in wheat and their specific functions in salt adaptation remain largely unknown. In this study, we performed a genome-wide identification, revealing 106 TaAT genes unevenly distributed across the wheat chromosomes. Transcriptomic analysis identified a subset of TaAT genes responsive to salt stress, among which TaNAAT1 (Nicotianamine Aminotransferase 1) showed the most distinct induction. Functional validation demonstrated that transgenic wheat lines overexpressing TaNAAT1 exhibited significantly enhanced growth performance under salt stress, as evidenced by improved shoot and root growth, higher chlorophyll content, and reduced oxidative damage compared to wild-type plants. Physiological assays revealed that TaNAAT1 overexpression was associated with higher accumulation of proline and soluble sugars, as well as elevated peroxidase (POD) activity, suggesting a possible role in osmotic adjustment and antioxidant defense. Mechanistically, we identified the bZIP transcription factor TaOBF1B as a direct upstream activator of TaNAAT1. Yeast one-hybrid, dual-luciferase, and EMSA assays confirmed that TaOBF1B binds to the G-box motif in the TaNAAT1 promoter to modulate its expression in response to salt stress. This study provides a comprehensive evolutionary and functional framework for the wheat AT gene family and identifies a novel TaOBF1B-TaNAAT1 regulatory module associated with salt tolerance, potentially involving metabolic adjustments that await further biochemical characterization.