Genome-wide identification and comparative analysis of genes encoding AAPs in apple (Malus x domestica Borkh.)

Amino acid permeases (AAPs) play important roles in plant amino acid transport and nitrogen metabolism. In this study, we carried a comprehensive analysis for apple genes encoding AAPs using bioinformatics and molecular biology. Eleven MdAAPs were identified by a genome-wide search and comparative genomic analysis revealed relatively conserved gene composition, transmembrane characteristics, and protein structures. Phylogenetic tree construction and analysis of the conserved motifs of MdAAPs and AtAAPs showed that AAPs can be classified into three groups (I, II, and III). We compared the promoters of the identified genes and did gene functional annotation and qRT-PCR and found a relationship between apple AAPs and nitrogen deficiency. The expression profile data implied that MdAAPs exhibit diversified distributions and functions in different tissues.