The PpIAA5-ARF8 Module Regulates Fruit Ripening and Softening in Peach

Abstract

Fruit ripening and softening are important physiological processes in fruit quality formation, and auxin is involved in regulating the ripening and softening process in peach fruit. Little research has been reported on the role of Aux/IAA (auxin/indole-3-acetic acid)-ARF (auxin response factor) protein interactions in the ripening process of peach fruit. The transcriptomics and RT–qPCR results revealed that PpIAA5 expression increased before ripening in peach fruits. Overexpression of PpIAA5 significantly represses the expression of peach fruit ripening- and softening-related genes PpPG and PpACO1 in peach fruit tissues using transient transformation. A yeast library and yeast two-hybrid screen yielded PpARF8, a protein that interacts with PpIAA5. The interaction relationship was further established using a bimolecular fluorescence complementation assay. Transient overexpression of PpARF8 in peach fruit tissues promoted the expression of PpPA, PpPG, and PpACO1. Furthermore, a tomato transient transformation assay validated that the PpARF8 gene promotes fruit ripening and softening. Taken together, our results suggest that the PpIAA5-ARF8 signaling module can affect the ripening and softening of peach fruits.