Expression of chitinase genes in entomopathogenic fungus Metarhizium anisopliae during the different stages of pathogenesis using quantitative real-time RT-PCR
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The penetration of entomopathogenic fungus into the cuticle of an insect is the initial and critical step of infection. Since, insect cuticle mainly includes chitin fibrils, the cuticle degrading chitinases play the main role in fungal pathogenicity. The involvement of CHI2 (which encodes a 44 kDa chitinase) and CHI3 (which encodes a chitinase with endo- and exochitinase activity) genes in pathogenesis of Metarhizium anisopliae have been proven by overexpression of these genes. To investigate the role of chitinase genes during pathogenesis, gene expression analyses were conducted during the different stage of M. anisopliae infection in Spodoptera litura larvae using quantitative real-time RT-PCR. Sampling were at 0, 2, 12, and 24 hours after infection, when the infected larvae reached the moribund stage, when white mycelium emerged from the insect cadavers, when few conidia had formed on the mycelium, and when the cadavers were mummified by the conidia. The expression levels of CHI2 and CHI3 genes increased significantly during the emergence of mycelium from the cadavers and at the beginning of conidiogenesis, but decreased at later stage. In the present study, the high expression of these genes during the late stages of pathogenesis when mycelia emerged and subsequently conidiated on the cadavers obviously shows their important roles at the post-mortem stages too.
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