Abstract
The interactions between jasmonates [jasmonic acid (JA) and methyl jasmonate (MeJA)] and abscisic acid (ABA) were investigated in 'Tsugaru' apple (Malus pumila Mill. var. domestica Schneid.). In Exp. 1, discs from pulp excised 93 days after full bloom (DAFB)(preclimacteric), 112 DAFB (climacteric), and 133 DAFB (postclimacteric) were collected and placed in petri dishes containing a solution of 0.4 M mannitol with a combination of MeJA, ABA, and aminoethoxyvinylglycine (AVG). Jasmonates, ABA, and ethylene levels in the discs were measured at 0, 24, 48, and 72 hr after the initiation of treatment. At the climacteric and postclimacteric stages, the ABA treatment increased endogenous JA concentration and decreased it when combined with AVG. This result suggests that ethylene may be related to the induction of endogenous JA by ABA. MeJA treatment decreased endogenous ABA concentration from 93 to 133 DAFB, whereas AVG had no influence. This result also demonstrates that jasmonates may influence endogenous ABA synthesis independently from ethylene. In Exp. 2 when discs with skins from the apple pulp samples from preclimacteric, climacteric, and postclimacteric stages were excised, cultured for 7 days under light on B5 media containing MeJA, and the combination of MeJA and AVG was investigated, MeJA and MeJA combined with AVG stimulated greater anthocyanin accumulation in both sampling stages compared to the untreated control ; the combination of MeJA and AVG resulted in a lower concentration of anthocyanin than that of only MeJA at the preclimacteric and postclimacteric stages. Therefore, in most cases, jasmonates may be related to anthocyanin formation in apples in the presence and absence of ethylene.
