Abstract

Peach (Prunus persica L. Batsch) was chosen to shed light on the physiological role of jasmonates (JAs) during fruit development and ripening. To this aim, the effects of methyl jasmonate (MJ, 0.80 mM) and propyl dihydrojasmonate (PDJ, 0.44 mM), applied in planta at the S1/S2 transition, on the time course of ethylene production and fruit quality traits, on gene expression of the first specific enzyme in the biosynthesis of jasmonic acid, allene oxide synthase (PpAOS1) and on the expression of some ethylene biosynthetic and perception genes were evaluated in the seed and mesocarp separately at harvest. Exogenously applied JAs affected ripening. Both compounds enhanced the transcription of PpAOS1 and down-regulated some ripening-related genes, such as 1-aminocyclopropane-1-carboxylic acid synthase (PpACS1) and 1-aminocyclopropane-1-carboxylic acid oxidase (PpACO1). MJ also altered the expression of the ethylene perception and signalling genes PpETR1, PpETR2 and PpERF2. Thus, in peach fruit, early application of MJ and PDJ led to a ripening delay due to a strong interference with ethylene-related gene expression in the seed and mesocarp of treated fruit at harvest.