Effect of methyl jasmonic acid on peach fruit ripening progress

Abstract

In order to investigate the role of jasmonates (JAs) during the ripening of peach fruit, two concentrations of methyl jasmonate (MeJA, 10 and 100mM) were evaluated using field system. Fruit quality parameters, such as the contents of anthocyanin, volatile compounds and cell wall enzymes, and the transcriptional profiles of several ripening-related genes were analyzed. Our results showed that MeJA promoted fruit chlorophyll degradation and anthocyanin accumulation, volatile compounds enhancement, but it would also delay fruit softening through regulation cell wall enzymes activities of PG and cellulase. MeJA increased fruit anti-stress because of the promotion of SOD, POD, CAT, PPO enzyme activities. MeJA reduced fruit endogenous ethylene content, although ethylene accelerated fruit softening and decreased titratable acidity that resulted in fruit ripening. MeJA altered the expression profiles of its biosynthesis pathway genes of PpLOX, PpAOS, and PpOPR3, which resulted the accumulation of JA accumulation in peach fruit. MeJA also increased the expression levels of anthocyanin-associated genes PpMYB, PpPAL, PpCHS, PpCHI, PpF3H, PpDFR, and PpUFGT. MeJA increased chlorophyll degradation gene of PpPAO, as well as decreased its biosynthesis gene of PpPORC, which led to chlorophyll reduction. However, ethylene had a reverse effect on the genes’ expression levels, and it inhibited anthocyanin accumulation. Ultimately, heterologous expression peach PpAOS in strawberry showed that JA promoted fruit anthocyanin accumulation. The present findings suggest that JA promotes peach fruit ripening through regulation anthocyanin accumulation, which is different from the way triggered by ethylene in regulation peach fruit ripening.