The effects of JAs on the time-course of their own biosynthesis and endogenous levels was then evaluated. In control fruit, the PpAOS1 message was initially low and then increased gradually to reach the highest amount at second harvest (Fig. 3A). One day after applications, both MJ and PDJ equally and strongly enhanced PpAOS1 mRNA abundance relative to controls. Subsequently, this stimulation persisted, though attenuated, only for MJ. In control fruit, jasmonic acid content slowly decreased up to first harvest and then rose at second harvest (twice control levels; Fig. 3B). In treated fruit, both MJ and PDJ caused an early (1 d after treatments) and transient accumulation (;30%) of jasmonic acid; thereafter, its concentration did not change until, at second harvest, it fell well below (>50%) control levels. Overall, JA-treated fruit displayed a decreasing trend in jasmonic acid concentration. Only traces of MJ were detectable in treated and control fruit samples (data not shown)