Genome-Wide Analysis of Soybean Apyrase Gene Family and Functional Characterization of GmAPY1-4 Responses to Aluminum Stress

Apyrases (APYs) directly regulate intra- and extra-cellular ATP homeostasis and play a key role in the process of plants adapting to various stresses. In this study, we identified and characterized soybean APY (GmAPY) family members at the genomic level. The results identified a total of 18 APYRASE homologous genes with conserved ACR domains. We conducted a bioinformatics analysis of <i>GmAPYs</i>, including sequence alignment, phylogenetic relationships, and conserved motifs. According to the phylogenetic and structural characteristics, <i>GmAPYs</i> in soybeans are mainly divided into three groups. The characteristics of these <i>GmAPYs</i> were systematically evaluated, including their collinearity, gene structure, protein motifs, cis-regulatory elements, tissue expression patterns, and responses to aluminum stress. A preliminary analysis of the function of <i>GmAPY1-4</i> was also conducted. The results showed that GmAPY1-4 was localized in the nucleus, presenting relatively high levels in roots and root nodules and demonstrating high sensitivity and positive responses under aluminum stress circumstances. Further functional characterization revealed that the overexpression of GmAPY1-4 in hairy roots not only induced root growth under normal growth conditions but also significantly prevented root growth inhibition under aluminum stress conditions and contributed to maintaining a relatively higher fresh root weight. By contrast, RNAi interference with the expression of GmAPY1-4 in hairy roots inhibited root growth under both normal and aluminum stress conditions, but it exerted no significant influence on the dry or fresh root weight. To sum up, these findings support the significant functional role of GmAPY1-4 in root growth and the aluminum stress response. These findings not only enhance our comprehension of the aluminum stress response mechanism by identifying and characterizing the APY gene family in the soybean genome but also provide a potential candidate gene for improving aluminum tolerance in soybeans in the future.