Roles of ERF2 in apple fruit cuticular wax synthesis

Ethylene response factors 2 (ERF2) belongs to the AP2/ERF transcription factor family and plays key roles in ethylene signal transduction. The roles of MdERF2 in apple (Malus × domestica) cuticular wax synthesis regulated by ethylene were studied in this work. Result shows that MdERF2 overexpression (ERF2-OE) up-regulated the expression levels of wax-related synthetic genes long-chain acyl-CoA synthetase 2 (MdLACS2), Wax synthase1 (MdWSD1), Eceriferum 4 (MdCER4) and Eceriferum 6 (MdCER6), while has no effect on the transcription of Eceriferum 1 (MdCER1), and shows different regulation effects on the expression levels of mid-chain alkane hydroxylase 1 (MdMAH1) between calli and fruit. Furthermore, different MdERF2 expression levels changed the apparent structure of the apple cuticular wax and positively regulated the total wax accumulation. ERF2-OE also increased alkane and alcohol production but decreased acid and ester contents. Thus, ethylene regulated the synthesis of apple cuticular wax at the transcriptional level through MdERF2, thereby altering the wax structure and composition.