Genome-Wide Identification of TaSAUR Gene Family Members in Hexaploid Wheat and Functional Characterization of TaSAUR66-5B in Improving Nitrogen Use Efficiency

Excessive input of nitrogen fertilizer not only causes a great waste of resources but brings about a series of ecological and environmental problems. AlthoughSmall Auxin Up-regulatedRNAs(SAURs) participate in diverse biological processes, the function ofSAURsin the nitrogen starvation response has not been well-studied. Here, we identified 308TaSAURs in wheat and divided them into 10 subfamilies. The promoter regions of mostTaSAURscontain hormone responsive elements, and their expression levels change under the treatment of different hormones, such as IAA, MeJA, and ABA. Interestingly, overexpression of one of theTaSAURfamily members, a nitrogen starvation responsive gene,TaSAUR66-5B, can promote the growth ofArabidopsisand wheat roots. In addition, overexpression ofTaSAUR66-5BinArabidopsisup-regulates the expression levels of auxin biosynthesis related genes, suggesting that overexpressionTaSAUR66-5Bmay promote root growth by increasing the biosynthesis of auxin. Furthermore, overexpression ofTaSAUR66-5Bin wheat can increase the biomass and grain yields of transgenic plants, as well as the nitrogen concentration and accumulation of both shoots and grains, especially under low nitrogen conditions. This study provides important genomic information of theTaSAURgene family and lays a foundation for elucidating the functions ofTaSAURsin improving nitrogen utilization efficiency in wheat.Keywords:TaSAURgene family;TaSAUR66-5B;root;nitrogen utilization efficiency