Research On The Different Expression Of Pathogenicity-Related Genes Of Isaria Fumosorosea

Isaria fumosorosea is one of the widely used entomopathogenic fungi in biological control. This strain plays important role in biological control of Plutella xylostella. In our previous study, an isolate of I. fumosorosea(IFCF01) with very high pathogencity against P. xylostella was identified. In order to have a further understand of the pathogenesis of I. fumosorosea, at the same time make full use of this strain, we use the technology of RT-PCR to identify the expression levels of the 8 potential pathogenic genes during pathogenesis of I. fumosorosea and deduced the different functions of these pathogenic genes. The research of the expression levels of potential pathogenic genes during pathogenesis of I. fumosorosea can help us to have a deeper understand of the gene functions and the main pathogenic gene. Furthermore, it can help us to elucidate the underlying molecular mechanism of this special I. fumosorosea strain toward P. xylostella. The main results were summarized as follows:During the early stage of pathogenesis of I. fumosorosea, there are three pathogenic genes participating in the pathogenesis of insects, namely, class III chitinase Chi A1(Chi A Ⅲ), L-Serine dehydratase(L-Ser) and perilipin MPL1-like protein(MPL-1). The results revealed that:(1) The m RNA relative expression of gene Chi AⅢ was up regulated significantly(P<0.05) at the stages of 12 h, 30 h and 36 h after infection and down regulated at the stage of 5 d, 10 d when compared with the control.(2) The m RNA relative expression of gene L-Ser was up regulated significantly at the stage of 12 h after infection when compared with the control and other groups.(3) At the stage of 12 h after infection, the expression of gene MPL-1 was up regulated IV significantly when compared with the control. MPL-1 was down regulated at the other stages of the infection.During the early stage of pathogenesis of I. fumosorosea, there are five pathogenic genes participating in the pathogenesis of insects, namely, c AMP-dependent protein kinase regulatory submit(PK), patatin-like phospholipase(PLP), adenylate cyclase(ADC), MAP kinase kinase(MAPKK) and Mmc protein(Mmc). The results revealed that:(1) The expression of gene Mmc was upregulated in all the stages after infection except the 15 d when compared with the control and other groups. And the stage of 10 d after infection was up regulated significantly.(2) At the stages of 12 h, 24 h, 30 h and 36 h after infection, the m RNA relative expression of gene ADC was down regulated compared with that in control. However, at the stages of 5 d, 10 d and 15 d after infection, the m RNA relative expression of gene ADC was up regulated compared with that in control.(3) The m RNA relative expression of gene PLP expresses steadily at the early and middle stages of infection, when it went to the 10 d and 15 d after infection, the relative expression of PLP began upregulated significantly.(4) At the stages of 12 h, 24 h, 30 h and 36 h after infection, the m RNA relative expression of gene PK was down regulated compared with that in control. However, at the stages of 5 d, 10 d and 15 d after infection, the m RNA relative expression of gene PK was up regulated compared with that in control.(5) The m RNA relative expression of gene MAP was down regulated at all the stages after infection. And the gene relative expression level were under the expression of control during all stages of the infection except the stage of 15 d after infectionIn conclusion, only MAPKK was down regulated during all stages of the pathogenesis of I. fumosorosea while other eleven potentially pathogenic related genes were up regulated during different stages of infection. The m RNA relative expression of Chi AⅢ, L-Ser and MPL-1 were up regulated significantly at the stages of 12 h after infection, indicated these three genes participate and functioned at the early stage of pathogenesis of I. fumosorosea. The m RNA relative expression of PK, PLP, ADC and Mmc were up regulated significantly during the late stages of the pathogenesis of I. fumosorosea(5 d,10 d,15 d), indicated these four genes participated and functioned at the late stage of the pathogenesis of I. fumosorosea.