PrupeFUL4 regulates ripening and softening of peach fruits through ethylene biosynthesis

AP1/FUL is a subfamily member of the MADS-box transcription factor that plays a vital role in plant growth and development. In our study, five AP1/FUL subfamily members were identified in the peach genome. One member clustered into the euAP1 clade and is named PrupeAP1 , and the other four members clustered into the euFUL clade and are named PrupeFUL1-4 . PrupeAP1 was specifically expressed in flowers, PrupeFUL1, 2, 3 were mainly expressed in leaves and PrupeFUL4 was highly expressed in fruits, whereby the expression level was upregulated during ripening and softening processes. Inhibition of PrupeFUL4 expression in peach fruits by virus-induced gene silencing (VIGS) led to delayed fruit softening and significant suppression of the expression of PrupeACO1 and PrupeACS2 ; while PrupeFUL4 overexpression accelerated fruits softening with the significant upregulation of PrupeACO1 expression. Our results indicate that PrupeFUL4 regulates ripening and softening of peach fruits, and this is achieved through regulation of the ethylene biosynthesis pathway.