Genomic insights into threonine aldolase genes in wheat: Characterization and expression analysis during grain filling under drought stress

Threonine aldolase is important in amino acid metabolism. This study characterized the threonine aldolase genes in wheat by identifying THA genes and examining their expression profiles during grain-filling under drought stress. Querying the wheat genome database with the Arabidopsis THA protein retrieved 15 non-redundant wheat homologs, of which five putative homologs harbored a threonine aldolase domain. The identified TaTHA genes are located on chromosome 2 and show a complex distribution pattern among wheat subgenomes, with possible duplication events in the A and B genomes. Structural analysis revealed a rather conserved exon-intron organization, together with physicochemical properties, while motif analysis revealed two novel wheat-specific motifs. Tissue and development expression profiling revealed that TaTHA1 and TaTHA2 were expressed at high levels, indicating their importance for the core metabolic processes, while the other three genes, TaTHA3, TaTHA4, and TaTHA5, were expressed in a tissue-specific manner. Subsequently, upregulation of the expression of THA genes in specific grain-filling stages during drought stress was found, indicating a role in the regulation of threonine metabolism, although no differences in threonine content were found. These results shed lights on the functional roles of THA genes in wheat and their potential involvement in stress responses, providing important information that can be used for crop improvement and breeding strategies.