Effects of pre- and post-harvest application of salicylic acid or methyl jasmonate on inducing disease resistance of sweet cherry fruit in storage

Pre-harvest treatments with 2 mM salicylic acid (SA) and 0.2 mM methyl jasmonate (MeJA) significantly reduced lesion diameters on sweet cherry fruit caused by Monilinia fructicola compared with control post-harvest treatments. Pre-harvest treatment of sweet cherry with SA or MeJA induced β-1,3-glucanase, phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities during the early storage time. The efficacy of inducing resistance in sweet cherry fruit pre-harvest-treated with SA or MeJA to M. fructicola was better than that for fruit with post-harvest treatments, especially, at 25 °C. Activities of β-1,3-glucanase and PAL in SA- or MeJA-treated cherry fruit stored at 25 °C for both pre- and post-harvest treatments were significantly higher than those in fruit stored at 0 °C. SA with a concentration of 2 mM showed direct fungitoxicity on M. fructicola and significantly inhibited mycelial growth and spore germination of the pathogen in vitro. MeJA at 0.2 mM had little inhibitory effect on mycelial growth and spore germination of M. fructicola. The fruit treated with MeJA pre-harvest expressed higher activity of β-1,3-glucanase and PAL than fruit treated with SA and the control during the early storage time.