Study On The Mechanisms Involved In The Infection Of Grapes By Talaromyces Rugulosus O1 And The Response Of Grapes To The Infection

Grape is one of the important economic fruits in our country.Grapes are susceptible to fungal pathogens for its high content of water and sugar,which causes huge economic losses.The pathogens involved in postharvest diseases of grapes include some species of Aspergillus genus and Penicillium genus,and most of them are considered to be the producer of ochratoxin A(OTA).Therefore,the control of postharvest diseases is very important for the development of the grape industry,and understanding the mechanisms involved in the infection of grapes by pathogens and the response of grapes would provide new ideas for the biocontrol of postharvest diseases of grapes.Talaromyces rugulosus O1,an OTA-producing pathogen,was isolated from decay grapes by our research team.The aims of this study were to investigate the mechanisms involved in the infection of grapes by T.rugulosus O1 and response of grapes.The main results were as follows:(1)T.rugulosus O1 showed the ability of infecting grapes at 4? and 20?,especially at 20?.Most of the spores germinated and formed bud tubes after infecting grapes for 18 h,and a large number of mycelia extended out after infecting grapes for 36 h.OTA produced by T.rugulosus O1 accumulated in the wound of grapes in the process of infection.(2)OTA induced rot symptoms of grapes and promoted the infection of grapes by T.rugulosus O1.T.rugulosus O1 produced polygalacturonase(PG),pectin methylgalaturnae(PMG),C1 enzyme(C1),Endo-1,4-?-D-glucanase(Cx)and ?-glucosidase(?-G)in disease tissues of grapes,and the change in the expression level of genes encoding PG and ?-G were consistent with the enzyme activities.Furthermore,the activities of resistance related enzymes including polyphenoloxidase(PPO),catalase(CAT),peroxidase(POD),phenylalanine ammonialyase(PAL)improved relatively in grapes infected by T.rugulosus O1,and these results were consistent with the expression levels of these genes.(3)The mechanism involved in the infection of grapes by T.rugulosus O1 was analyzed through transcripteome technology.The results showed that the expression level of many genes of T.rugulosus O1 was up-regulated after infecting grapes for 18 and 36 h,including 5 genes related to cell wall degradation,1 gene related to OTA synthesis,1 gene related to pH regulation,2 genes related to oxidation reaction,and 4 genes related to the effect of protein.(4)The mechanism involved int the response of grapes to T.rugulosus O1 was also analyzed based on transcripteome.The results indicated that the expression level of many genes of grapes was significantly upregulated after being infected by T.rugulosus O1 for 18 and 36 h,such as some genes related to cell wall defense,PTI immune response,phytolectin,pathological-related protein(PR),and flavonoids biosynthesis.