Mechanisms Of Induced Resistance Of Fruit In Response To Antagonist Yeasts And Exogenous Salicylic Acid

Postharvest diseases of fruits and vegetables cause major losses in food production. Treatments with antagonistic yeasts and salicyclic acid (SA) suggested that intensification of defense mechanisms had potential in reducing fruit pre- and post-harvest decay. Here, we provide evidence that fruit treated with antagonist Pichia membranefaciens and SA showed a significant decrease in the symptom of blue mold rot caused by Penicillium expansum. The results were presented as following:1. The immersion of sweet cherry fruit in P. membranefaciens at a concentration of 5×107 cells?ml-1 or in SA at 0.5 mM for 10 min reduced the incidence of decay and lesion sizes. Both treatments affected the activities of antioxidant proteins. Treatments with yeast and SA also changed the expression degree of POD isozymes and total protein. Light microscopy and scanning electron microscopy (SEM) observation indicated that P. membranefaciens attach to the hyphae of P. expansum tightly in vitro and loosely in vivo.2. We developed a simple protocol, which has given reproducible 2-DE results for a variety of fruit, including harvested mango, peach, sweet cherry, apple and jujube. We further reported on the use of detailed proteomic analyses to reveal changes in peach fruit proteome induced with 1×108 cells?ml-1 P. membranefaciens or 0.5 mM SA. The results indicated that both treatments delayed the initiation infection in harvested peach fruit and resulted in lower lesion diameter. A total of 31 polypeptides whose abundance changed in response to the elicitors were identified 1 d after the treatments. These altered proteins attribute to metabolism, defense response, transcription, energy metabolism and cell structure. Among them, four antioxidant proteins and two pathogenesis-related (PR) proteins coordinately...