Genome-wide characterization of L-aspartate oxidase genes in wheat and their potential roles in the responses to wheat disease and abiotic stresses.

L-aspartate oxidase (AO) is the first enzyme in NAD biosynthesis and is widely distributed in plants, animals, and microorganisms. Recently, AO family members have been reported in several plants, including and . Research on AO in these plants has revealed that AO plays important roles in plant growth, development, and biotic stresses; however, the nature and functions of AO proteins in wheat are still unclear. In this study, nine genes were identified in the wheat genome sequence alignment and conserved protein domain analysis. These nine wheat genes () were distributed on chromosomes 2, 5, and 6 of sub-genomes A, B, and D. Analysis of the phylogenetic relationships, conserved motifs, and gene structure showed that the nine were clustered into three groups, and the in each group had similar conserved motifs and gene structure. Meanwhile, the subcellular localization analysis of transient expression mediated by Agrobacterium tumetioniens indicated that TaAO3-6D was localized to chloroplasts. Prediction of cis-elements indicated that a large number of cis-elements involved in responses to ABA, SA, and antioxidants/electrophiles, as well as photoregulatory responses, were found in promoters, which suggests that the expression of may be regulated by these factors. Finally, transcriptome and real-time PCR analysis showed that the expression of belonging to Group III was strongly induced in wheat infected by during anthesis, while the expression of belonging to Group I was heavily suppressed. Additionally, the inducible expression of belonging to Group III during anthesis in wheat spikelets infected by was repressed by ABA. Finally, expression of almost all was induced by exposure to cold treatment. These results indicate that TaAOs may participate in the response of wheat to infection and cold stress, and ABA may play a negative role in this process. This study lays a foundation for further investigation of genes and provides novel insights into their biological functions.