| Pears occupy an important position in the world's fruits,but they are easily damaged during harvest,storage,transportation and shelf life for they are brittle and juicy,which results great economic losses.The main pathogens causing postharvest diseases of pears are Penicillium expansum and Botrytis cinerea.Traditionally,chemical fungicides are often used to control postharvest diseases of pears,but the residues of chemical fungicides are harmful to consumers.With the emphasis on food safety,it is an urgent task to study efficient and safe antagonistic microbial agents to replace chemical fungicidesIn this study,an antagonistic yeast with good biocontrol eff-icacy on postharvest blue mold of pears was isolated,selected and identified from a pear orchard in Zhenjiang,Jiangsu province.The mechanism of controlling postharvest diseases of pears was discussed,and the physiological and molecular mechanisms related to the induction of pears resistance were mainly studiedResults of this study were as follows:(1)Four strains of antagonistic yeast,YA,YB,YC and YD,were isolated from pear orchard.The effects on the control of postharvest blue mold of pears was tested by using the above yeast suspension at 1 × 108 cells/mL.It was found that the best control strain was YD,W.anomalus.Compared with the control(99%),the disease incidence of treatment of W.anomalus was only 17.6%.The safety and non-toxic of W.anomalus was tested by acute oral toxicity test.Its growth curve was determined to make sure the incubation time(2)The efficacy of W.anomalus to control blue mold of pears was affected by the concentration of the W.anomalus.Within a concentration range,the higher of the concentration,the better of the efficacy.W.anomalus decreased the natural decay rate of pears effectively without adverse influence on its storage quality.(3)W.anomalus could rapidly colonize in the wounds of pears whether at 20? or 4?W.anomalus controlled the spore germination rate of P.expansum in vitro experiment effectively,and the efficacy was also affected by the concentration of W.anomalus.W.anomalus could increase the activities of polyphenol oxidase(PPO),peroxidase(POD),catalase(CAT)and chitinase(CHI)of pears and the expression level of their defense-related genes were also up-regulated(4)The differentially expressed proteins of pears induced by W.anomalus were analyzed by proteomic technique,in which 113 proteins were up-regulated and 82 proteins were down-regulated.A total of 29 protein spots with significant differences were identified(average fold change>1.5,p<0.05).These differentially expressed proteins play roles in the biological process,molecular function,and cellular component of pears,respectively.Among them,PR family proteins,cytosolic ascorbate peroxidase,chitinase and ?-1,3-glucanase,and and other defense-related proteins were up-regulated,which indicated that W.anomalus induced resistance of pears and were conducive to defense the infection of pathogens(5)The differentially expressed genes of pears induced by W.anomalus were analyzed by using transcriptomic technology.1076 differentially expressed genes were identified,of which 556 were significantly up-regulated and 520 were significantly down-regulated.GO classification and KEGG analysis were performed on these differentially expressed genes.The term which was enriched significantly and involved in plant resistance in GO classification were membrane part,electron carrier activity,response to stimulus,signaling and immune system processes.In the KEGG analysis,differentially expressed genes of pears induced by W.anomalus were involved in jasmonic acid metabolism,flavonoid biosynthesis,and carbon metabolism to induce the resistance of pears. |
PDF Full Text Request