井冈霉素对水稻纹枯病菌细胞壁降解酶活性和可溶性蛋白的影响

Effects of Jinggangmycin on Cell Wall Degrading Enzyme Activity and Soluble Proteins of Rhizoctonia solani Kühn

为进一步阐明井冈霉素防治水稻纹枯病的作用机制,研究了井冈霉素对水稻纹枯病菌（Rhizoctonia solani Kühn）多聚半乳糖醛酸酶（PG）、纤维素酶（Cx）和果胶甲基半乳糖醛酸酶（PMG）3种细胞壁降解酶活性以及菌丝可溶性蛋白的影响。结果表明：与空白对照相比,井冈霉素在质量浓度分别为20、100、500μg/mL时,均不同程度地降低了3种细胞壁降解酶的活性。当井冈霉素质量浓度为20μg/mL和100μg/mL时,与空白对照相比,Cx或PG的活性下降程度分别达到显著水平。在各供试浓度下,PMG的活性与空白对照相比均未达显著水平。通过聚丙烯酰胺凝胶电泳分析,每个处理的病菌菌丝可溶性蛋白均可分辨出20条谱带,较为清晰的谱带有16条。与空白对照相比,不同处理之间的病菌菌丝可溶蛋白谱带数目和迁移率均相同,但谱带颜色的深浅和谱带的粗细有差异,表明蛋白种类一致,只是含量不同。在蛋白分子质量为90 u处,井冈霉素质量浓度为500μg/mL时的谱带明显增强;在分子质量为16-35 u之间有6条谱带,当井冈霉素质量浓度为500μg/mL时的谱带明显减弱。这说明井冈霉素质量浓度为500μg/mL时,对病菌菌丝可溶性蛋白有一定的影响;在质量浓度为20μg/mL和100μg/mL时,对病菌菌丝可溶性蛋白无显著影响。

To further elucidate the mechanism of Jinggangmycin in controlling rice sheath blight,effects of Jinggangmycin on three cell wall degrading enzymes（CWDEs）,i.e.polygalacturnase（PG）,cellulase（Cx） and pectin methyl-galacturonase（PMG）,and soluble mycelial proteins of Rhizoctonia solani,the causal agent of rice sheath blight,were investigated in this research.The results showed that the enzyme activities of all three CWDEs decreased in different degrees at all three tested concentrations of 20,100,500 μg/mL of Jinggangmycin compared with the blank control（absence of Jinggangmycin,the same in later text）.Jinggangmycin at the concentration of 20 μg/mL or 100 μg/mL caused significant reduction at P=0.05 level in enzyme activity of Cx or PG,respectively,when compared with the blank control;however,there was no significant difference at P=0.05 level in enzyme activity of PMG at different concentrations of Jinggangmycin compared with the blank control.By using polyacrylamide gel electrophoresis technique,soluble mycelial proteins of each treatment displayed a pattern of 20 protein-bands with 16 clearer ones when the pathogen was cultured at above mentioned three concentrations of Jinggangmycin.The numbers and the mobility rates of protein-bands were identical,whereas the colour darkness and band width were somewhat different compared with those of the blank control,indicating that the kinds of protein were the same,but the protein contents were different;the band with molecular weight of 90 ku was obviously strengthened at 500 μg/mL,whereas the 6 bands with molecular weights between 16 u and 35 u were obviously weakened at the same concentration,which indicated that Jinggangmycin had certain effect on the soluble mycelial proteins at 500 μg/mL,but no significant effects on the soluble mycelial proteins were observed at concentrations of 20 μg/mL and 100 μg/mL.Taken all together,our study revealed that Jinggangmycin had an impact on CWDEs and soluble mycelial proteins of R.solani weakened the infection of R.solani to rice,and thus it is speculated that this may be one of the mechanisms of rice sheath blight control of Jinggangmycin.