Effect of yeast antagonist in combination with methyl jasmonate treatment on postharvest anthracnose rot of loquat fruit

The beneficial effect of methyl jasmonate (MeJA) on the antagonistic yeast Pichia membranefaciens for control of anthracnose rot caused by Colletotrichum acutatum in postharvest loquat fruit and the possible mechanisms were investigated. The results indicated that the biocontrol activity of P. membranefaciens at 1 x 10(8) colony-forming units ml(-1) on anthracnose rot was enhanced by 10 mu mol MeJA treatment. The combined treatment of P. membranefaciens with MeJA resulted in a remarkably improved control of the disease in comparison with the treatment of P. membranefaciens or MeJA alone. P. membranefaciens in combination with MeJA induced higher activities of two defense-related enzymes chitinase and beta-1,3-glucanase in loquat fruit than applying the yeast or MeJA alone. The in vitro experiment showed that the addition of 10 mu mol l(-1) MeJA to the suspensions of P. membranefaciens significantly inhibited spore germination and germ tube elongation of C acutatum than the yeast or MeJA alone. In addition, MeJA enhanced the population of P. membranefaciens both in vitro and in the wounds of the loquat fruit. These results suggested that MeJA could improve the biocontrol activity of P. membranefaciens on anthracnose rot in loquat fruit and the improved control of the disease by MeJA is directly because of the higher inhibitory effect on pathogen growth and the increased population size of antagonist, and indirectly because of the enhanced disease resistance in loquat fruit by the combination treatment. (C) 2009 Elsevier Inc. All rights reserved.