Study On Biocontrol Of Postharvest Decay Of Table Grapes Caused By Penicillium Rubens And The Possible Resistance Mechanisms By Yarrowia Lipolytica

China is a big producer of grape.Grape with tempting color and soft pulp is suitable for all people.However,grape is easilly subjected to pathogen infection during the process of storage,which causes tremendous losses.Penicillium spp.is a common pathogenic fungus that produces toxic secondary metabolite ochratoxin A?OTA?.Recently,the control of postharvest decay of grapes is mainly based on chemical fungicides.However,due to the developmemt of chemical fungicide-resistant of pathogenic fungus and the residues on fruits harming to the health of consumers,so a substituted method in controlling postharvest decay of fruit needs to be explored.At present,antagonistic yeast has been using in controlling postharvest decay of fruit,and has prospective to replace chemical methods.Yarrowia lipolytica was isolated from grape peels by our laboratory.Penicillium rubens was also isolated from the rotten grapes.The aims of this study were to investigate the biocontrol efficacy of Y.lipolytica in controlling postharvest decay caused by P.rubens in grapes and the possible resistance mechanisms,further explore molecular regulation resistance mechanism.The main research resluts were as follows:?1?Y.lipolytica significantly inhibited postharvest decay of grapes by P.rubens compared with the control.The higher the concentrations of Y.lipolytica,the lower the decay incidence and the smaller the decay diameter of the grape wound;Y.lipolytica significantly reduced OTA content produced by P.rubens.After 17 days of treatment,OTA content of grapes treatment with Y.lipolytica was only 0.33 ng/wound;In vitro experiment,the result showed that the higher the concentration of Y.lipolytica,the lower spore germination rate and the shorter germ tube length.?2?Whether 20°C or 4°C,Y.lipolytica colonized on the surface of grapes and maintained a high amount of yeast.Y.lipolytica could enhance defense-related enzyme activities of grapes,such as polyphenoloxidase?PPO?,ascorbate peroxidase?APX?,peroxidase?POD?,phenylalanine ammonialyase?PAL?,catalase?CAT?and?-1,3glucanase?GLU?,and the expression levels of these genes coding these corresponding enzyme were also increased in grapes treated with Y.lipolytica.?3?The proteomic analysis of Y.lipolytica-triggered grape was analyzed,and the results showed that 33 differentially expressed proteins?ratio>1.5?were identified,in which 25 proteins were up-regulated and 8 proteins were down-regulated.Resistant proteins were involved in the process of response to stress?heat shock protein 70 et al?,pathogenesis related?PR?allergenic proteins?PR4 type protein et al?,energy production and signal transduction?ATPase catalytic subunit A et al?and oxidoreductase?superoxide dismutase et al?.The expression of all of thse proteins were increased treated by Y.lipolytica.?4?The transcriptomics analysis of Y.lipolytica-triggered grape was analyzed,and the results showed that 616 differentially expressed genes?DEGs?were identified??log₂?Fold Change???3 and FDR<0.5?,in which expression levels of 384 genes were increased and expression levels of others were decreased.9 DEGs that were up-regulated were selected to verify the expression levels of these genes by RT-qPCR,including PR4,PR5,PR10,coding hypersensitivity protein,WRKY transcription factor,phytoprotein-related genes et al,in which PR4,PR5 and PR10 were corresponding to pathogenesis related allergenic proteins.