Responsive Mechanism of Salt‐Tolerant Spring Wheat Variety to Salt Stress During the Seedling Stage

ABSTRACT Spring wheat is predominantly cultivated in saline‐alkaline regions. However, little is known about the mechanisms underlying the salt tolerance of spring wheat. This study explored physiological and gene expression regulation mechanisms by which a salt‐tolerant spring wheat variety (QM‐1) resists salt stress during the seedling stage. Under salt stress, QM‐1 displayed higher root Na + concentration and root biomass but lower shoot Na + concentration than the control variety (NCY‐4). Increasing root biomass was helpful to reduce Na + influx into the shoots via Na + compartmentalization at the roots for QM‐1 under salt stress. Metabolomic analysis revealed that NCY‐4 had synthesis defects in many flavonoids in the leaves, while high flavonoid accumulation was a specific metabolic characteristic of QM‐1 under salt stress. Exogenous application experiments confirmed that exogenous application of quercetin‐7‐O‐glucoside alleviated salt stress damage in NCY‐4, whereas application of neither flavonoids nor carbohydrates alone can alleviate damage of salt stress to NCY‐4. Transcriptomics showed that many key flavonoid synthesis genes ( 4CL , CHS , ANR ), glycosyltransferase genes (responsible for flavonoid glycosylation), key carbohydrate metabolic synthesis genes, and flavonoid synthesis regulatory genes ( R2R3‐MYB , bHLH ) displayed significantly higher expression levels in the leaves of QM‐1 than in those of NCY‐4 under salt stress. The above data indicated that flavonoids, like quercetin‐7‐O‐glucoside, may play a critical role in QM‐1. In response to salt stress, the salt‐tolerant spring wheat variety enhanced whole‐plant tolerance by increasing root biomass and root/shoot ratio to improve ionic stress tolerance and by accumulating flavonoids in leaves to facilitate ROS scavenging.