Genome-Wide Identification of the ALMT Gene Family in Nine Rosaceae Species and Functional Analysis Associated with Organic Acid Accumulation in Prunus mume

ALMT (aluminum-activated malate transporter) proteins play crucial roles in the transport of organic acids and have significant implications for plant stress responses and development. While extensively studied in some plants, the characteristics and functional divergence of the ALMT gene family have not yet been thoroughly explored in Prunus mume and some other Rosaceae species. In this study, we systematically analyzed the ALMT gene family across nine Rosaceae species to explore their evolutionary relationships, structural characteristics, and functional roles. A total of 138 ALMT genes were identified and categorized into four groups based on a phylogenetic analysis. The motif analysis confirmed the accuracy of the phylogenetic grouping. The collinearity analysis indicated that whole-genome duplication events were the primary drivers of ALMT gene expansion in these species. Furthermore, the cis-acting element analysis revealed diverse regulatory elements associated with environmental responses, including abscisic acid, light, and jasmonic acid. The gene expression correlation analysis showed that PmALMT1 is primarily associated with malic acid accumulation, whereas PmALMT8 is related to citric acid accumulation. Further transient expression in Nicotiana benthamiana validated the above conclusion. This comprehensive analysis provides valuable insights into the evolution, function, and regulation of the ALMT gene family in Rosaceae species.