Roles of jasmonic acid in the development of sweet cherries as measured from fruit or disc samples

The effect of jasmonic acid (JA) on callus formation was investigated ondiscs taken from the pulp of sweet cherry fruit (Prunusavium L.). The discs were sampled at 16 days after full bloom(DAFB),22 DAFB, and 29 DAFB and cultured on B5 medium involving different combinationsof 1-naphthaleneacetic acid (NAA), N⁶-benzyl adenine (BA), and JA.Only at 16 DAFB, 1.0 M JA concentration increased callusweightgain relative to discs incubated without hormonal additives, although JAinhibited, or had no effect on callus formation, at 22 and 29 DAFB. The weightof the callus, which was subcultured, was also increased by 0.45–1.0M JA, without hormonal additives. Although the number of cellsincreased until 15 DAFB, after this time it did not change. These resultsdemonstrate that endogenous JA may be related to cell division in sweet cherryfruit. The interactions between JA and abscisic acid (ABA) were alsoinvestigated. Discs from pulp at 20 DAFB (immaturity), 32 DAFB (beforematuration), and 48 DAFB (maturation) were placed in petri dishes containing 10ml 0.4 M mannitol with JA or ABA. In addition, at 48DAFB, JA or ABA solutions had been absorbed by the fruit for 7 days via theshoot. ABA treatment did not influence endogenous JA concentrations in discs,with few exceptions. Although the ABA concentration in the fruit increased to2.2 times that of the control by ABA the 7 day treatment, endogenous JA failedto increase. Thus, ABA may not influence the JA pathway in sweet cherry fruit.Although the increase of endogenous ABA was observed in discs at earlier timesafter JA treatment, ABA concentration decreased in the fruit treated for 7 dayswith JA. This implies that the concentration of JA may influence ABA levels. JAtreatment did not influence anthocyanin accumulation, in spite of the increaseof JA in the fruit by the treatment. JA may not play a role in anthocyaninaccumulation in sweet cherry fruit.