Identification of EIL and ERF Genes Related to Fruit Ripening in Peach

Abstract

Peach (<i>Prunus persica</i>) is a climacteric fruit with a relatively short shelf life due to its fast ripening or softening process. Here, we report the association of gene families encoding ethylene insensitive-3 like (EIL) and ethylene response factor (ERF) with fruit ripening in peach. In total, 3 <i>PpEILs</i> and 12 PpERFs were highly expressed in fruit, with the majority showing a peak of expression at different stages. All three EILs could activate ethylene biosynthesis genes <i>PpACS1</i> and <i>PpACO1</i>. One out of the 12 <i>PpERFs</i>, termed <i>PpERF.E2</i>, is a homolog of ripening-associated <i>ERFs</i> in tomato, with a consistently high expression throughout fruit development and an ability to activate <i>PpACS1</i> and <i>PpACO1</i>. Additionally, four subgroup F PpERFs harboring the EAR repressive motif were able to repress the <i>PpACO1</i> promoter but could also activate the <i>PpACS1</i> promoter. Promoter deletion assay revealed that PpEILs and PpERFs could participate in transcriptional regulation of <i>PpACS1</i> through either direct or indirect interaction with various cis-elements. Taken together, these results suggested that all three <i>PpEILs</i> and <i>PpERF.E2</i> are candidates involved in ethylene biosynthesis, and EAR motif-containing <i>PpERFs</i> may function as activator or repressor of ethylene biosynthesis genes in peach. Our study provides an insight into the roles of EILs and ERFs in the fruit ripening process.