玫烟色棒束孢Pr1酶活力、Pr1酶基因表达量与其毒力的相关性

Correlation between Pr1 protease activity, Pr1 gene expression and strain virulence of Isaria fumosorosea

摘要:

丝氨酸弹性凝乳蛋白酶Pr1是一类能高效降解昆虫体壁蛋白的重要酶，其活力与虫生真菌的毒力有很大的关系。探索玫烟色棒束孢不同菌株Pr1酶活力、Pr1蛋白酶基因表达量与毒力的相关性对该菌的应用具有重要的意义。文中采用专一性短肽底物 Suc-Ala-Ala-Pro-Phe-pNA和荧光定量PCR分别测定了玫烟色棒束孢不同菌株的Pr1酶活和Pr1基因的表达量，并采用坡塔喷雾法测定了供试菌株对桃蚜的毒力。结果表明：不同供试菌株Pr1蛋白酶活力与其毒力的线性回归方程为y=3.64x+0.62，R2=0.432，两者呈正相关；供试菌株Pr1酶活力、Pr1基因表达量与毒力的回归方程为y=0.236+10.833x1–0.039x2 (x1=Pr1酶活力，x2=Pr1基因表达量)，R2=0.568，说明线性拟合方程能很好地反映原始数据；序列相关系数D-W为2.444，在0.05水平上相关显著，表明Pr1酶活力、Pr1基因表达量对毒力有显著影响；VIF=12.705表明Pr1酶活力、Pr1基因表达量存在中度多重共线性。因此建议将 Pr1蛋白酶的酶活力和Pr1基因表达量作为菌株毒力筛选时的重要指标。

Abstract:

Serine elastic chymotrypsin Pr1 is an enzyme that efficiently degrades insect body wall protein through its connection with the virulence of entomogenous fungi. Therefore, it is important to explore the relationship between the Pr1 protease activity, the Pr1 gene expression and the virulence of different strains of entomogenous fungi. Specific peptide substrate Suc-Ala-Ala-Pro-Phe-pNA and fluorogenic quantitative PCR were used for detecting Pr1 protease activity and Pr1 gene expression, and the slope spray method was used for evaluating the virulence of the fungi on the Myzus persicae. The results indicated that the linear regression equation of the Pr1 protease activity and the virulence of different strains were: y=3.64x+0.62, R2=0.432. It was shown that there is a positive correlation between the Pr1 protease activity and virulence of different strains. Moreover, the result of the multiple linear regression analysis between Pr1 protease activity, Pr1 gene expression and the virulence of different strains was: y=0.236+10.833x1–0.039x2 (x1 represents Pr1 protease activity while x2 represents Pr1 gene expression), R2=0.568, which suggested that the raw data could be represented by a linear fitting equation. The serial correlation coefficient was high (D-W was 2.444), indicating that Pr1 protease activity and Pr1 gene expression have great effect on the virulence of the fungi. Additionally, VIF=12.705, which shows that moderate multiple collinear exists between Pr1 protease activity and Pr1 gene expression. Therefore, Pr1 protease activity and Pr1 gene expression could be recommended as important indicators for strain virulence selection.