Genome-wide identification and characterization of AINTEGUMENTA-LIKE (AIL) family genes in apple (Malus domestica Borkh.)

AINTEGUMENTA-LIKE (AIL) genes play a key role in various growth and developmental processes in plants. Thus far, the genome-wide identification of AIL genes has been reported for some plant species. However, genome-wide identification of AIL genes has not been conducted in apple (Malus domestica Borkh.). The current study focused on a comprehensive analysis of the AIL genes in the apple genome (i.e., MdAIL genes). In total, 27 MdAIL genes in the apple genome were identified and then divided into four groups according to phylogenetic analysis. The chromosomal locations, gene and protein structures, and physicochemical characteristics of MdAIL genes were analyzed. Synteny analysis revealed that segmental duplication events played a major role in the expansion of the AIL gene family in apple. The analysis of cis-regulatory elements in MdAIL promoter regions indicated that most of the MdAIL genes are involved in embryo development and seed germination. Moreover, the analysis of tissue-specific expression patterns and transcript levels in adventitious bud regeneration indicated that MdAIL genes play an extensive regulatory role in apple growth and development, especially in the regulation of germination and adventitious bud regeneration from in vitro leaves of apple. In conclusion, this is the first genome-wide analysis of the AIL genes in apple. The current results may help in better understanding the evolution and function of MdAIL genes and thus facilitate further research on plant growth and development.