Isolation, Phylogeny and Expression Patterns of AP2-Like Genes in Apple (Malus x domestica Borkh)

The AP2/ERF family transcription factors (TFs) act as the nodes of a regulatory network in a plant's response to abiotic and biotic stress. AP2-like genes from apple (Malus x domestica Borkh), one of the most widely cultivated fruit trees worldwide, were identified and analysed in order to understand the transcriptional regulation through the AP2/ERF family TFs. Starting from the M. domestica database, 58 AP2-like TFs were identified by in silico cloning using the AP2/ERF TFs amino acid sequence of Arabidopsis thaliana as a probe. The AP2/ERF TFs from apple were classified into four subfamilies, DREB, ERF, AP2 and RAV. To establish detailed expression data of this gene family in apple, six kinds of tissue (bud, flower, fruit, leaf, root and stem) and cell culture were examined for the presence of AP2-like genes. Most of the apple AP2-like genes indicate some degree of tissue specificity and were most abundant in root followed by stem, and expression levels were low in leaf and in bud.