Genome-wide survey and expression analysis of the amino acid transporter gene family in poplar

Members of the amino acid transporters (AATs) gene family transported amino acid across cellular membranes and participated in various aspects of normal plant growth and developmental processes as well as environmental responses. To date, no overall analysis or expression profiling of the AAT gene family in Populus has been reported. An investigation of the Populus genome revealed 100 putative AAT genes. These genes were classified into 11 subfamilies based on phylogenetic analysis. In each subfamily, the constituent parts of gene structure and motif were relatively conserved. A total of 100 genes were distributed on 19 chromosomes with 18-pair segmental duplication and 19-gene tandem duplication events, indicating that segmental and tandem duplications contribute almost equally to the expansion of the PtAAT gene family. Analysis of the Ka/Ks ratios showed that the duplicated genes of the AAT family basically underwent purifying selection. The expression levels of the 17 amino acid/auxin permease (AAAP) subfamily genes under abiotic stresses and in different tissues were investigated by quantitative real-time PCR (qRT-PCR) to explore their stress-related and tissue-specific expression patterns. The qRT-PCR results to explore the precise role of individual PtAAT gene. This study presents a thorough overview of the Populus AAT gene family and provides a new perspective on the evolution of this gene family. The results indicate that AAT family genes may be involved in many plant responses to stress conditions. Additionally, this study provides a solid foundation for uncovering the biological roles of AAT genes.