玉米灰斑病菌与不同品种玉米互作后果胶酶活性的变化

Changes of Pectinase Activities after Interaction between Cercospora zeae-maydis and Different Maize Varieties

为了明确果胶酶在玉米灰斑病菌与寄主互作中所起的作用,采用比色法测定了玉米灰斑病菌06-09菌株与不同抗性玉米品种互作3代后,再分离菌胞内和胞外果胶酶[果胶甲基半乳糖醛酸酶(PMG)、果胶甲基反式消除酶(PMTE)]活性并分析其变化。结果表明,同一种酶、同一互作寄主、同一互作代数,胞外酶活性高于胞内酶,说明果胶酶(PMG和PMTE)主要以胞外酶形式起作用;互作单代,再分离菌果胶酶活性的变化均与寄主的抗感性无密切关系;与对照原菌株06-09比较,再分离菌PMTE活性的变化趋势是第1次互作后大部分升高,而第2、3次互作后则均降低;对于同一互作品种,PMG活性总体上随互作代数增加而升高,PMTE活性表现为第1次互作后明显高于第2次和第3次互作,第2次和第3次互作间酶活性差异不显著,说明病菌与同一寄主连续互作后,其致病性将发生改变。

The purpose of this study is to clarify the function of pectinase in interaction between Cercospora zeae-maydis and host plants.The chromometry and ultraviolet-visible spectrophotometer were used to detect the changes of pectinase （PMG and PMTE）activities after interaction between C.zeae-maydis and different maize varieties.The results showed that the extracellular enzyme activity was greater than the intracellular enzyme for the same enzyme,the same interaction host and the same interaction time,indicating that the extracellular pectinase played an important part. The changes of pectinase activities from isolates were not related with host resistance in every interaction.The PMTE activity of isolates after first interaction usually increased,but the enzyme activities after second and third interaction decreased in comparison with contrast strain 06-09. For the same maize variety,the PMG activity increased with the increase of interaction time,and the PMTE activity after first interaction was higher than that after second and third interaction, but the enzyme activities after second and third interaction did not show significant difference. These indicated that the pathogenicity of C.zeae-maydis changed after its consecutive interaction with the same maize variety.