玉蜀黍尾孢菌CzVelB基因功能分析

Functional Analysis of CzVelB Gene of Cercospora zeae-maydis

以获得的野生型和CzVelB敲除突变体菌株为供试菌株,分别对其进行生物学及致病力测定,在此基础上分析毒素和细胞壁降解酶的活性。结果表明,与野生型相比,敲除CzVelB后菌丝生长速率及颜色无明显差异,但产孢量下降56.6%,且孢子萌发率下降,萌发过程滞后1 h。致病性分析发现,敲除CzVelB后菌株致病性明显下降,病情指数、病斑大小,突变体均低于野生型。分析毒素对叶片的致病性发现,突变体所产生的毒素低于野生型产生的毒素。敲除突变体菌株ΔCzVelB及野生型菌株在活体内外均能产生5种细胞壁降解酶,其中敲除CzVelB后,5种离体病原菌细胞壁降解酶活性明显下降。分析侵染过程中5种细胞壁降解酶发现,CzVelB主要通过影响CX和PMG在接种前期12 h内起重要作用;在接种后期(72~96 h),CzVelB主要通过影响PGTE的活性调控玉蜀黍尾孢菌致病力。

The wild-type and CzVelB strains were used as test strains,biological,inoculation test and the activities of toxin and cell wall degrading enzyme were analyzed.The results showed that compared with the wild-type,there was no significant difference between knockout transformants in the growth rate,but the spore production and spore germination of the knockout transformants decreased obviously,and the germination process lagged 1h.The pathogenicity of transformants was significantly decreased,including the disease index and lesion size.Toxin assays results showed that it had a certain pathogenic effect on leaves,but the mutant was lower than that produced by the wild-type.CzVelB and wild-type strains produced 5 cell wall degrading enzymes,the CWDEs activity of C.zeaemaydis was affected after CzVelB knocked out.Cellulase(Cx)and Pectin methyl-galacturonase(PMG)played a role in the early stages of infection(12 h).Polygalacuronic acid trans-eliminase(PGTE)played a part in the late stage of infection(72 to 96 h).CzVelB regulates the pathogenicity of C.zeae-maydis mainly by affecting the activity of PGTE.