玉米茎腐病菌产生的细胞壁降解酶种类及其活性分析

 玉米茎腐病菌Pythium aphanidermatum、Fusarium graminearum能够产生一系列细胞壁降解酶,即果胶甲基酯酶(PE)、多聚半乳糖醛酸酶(PG)、果胶甲基半乳糖醛酸酶(PMG)、多聚半乳糖醛酸反式消除酶(PGTE)、果胶甲基反式消除酶(PMTE)和纤维素酶(Cx)。Fusarium graminearum产生的细胞壁降解酶活性明显高于Pythium aphanidermatum。病菌在活体内和活体外产生的细胞壁降解酶活性明显不同。酶动力学研究表明:Fusarium graminearum产生的各种细胞壁降解酶均有特定的最适反应条件。水解酶类的PG、PMG、Cx最大酶活的pH分别为6.0、5.0、6.0,温度分别为50、40、50℃;裂解酶类的PGTE和PMTE最大酶活的pH均为9.0,温度分别为30、20℃,与其它病菌产生的细胞壁降解酶的特性基本相同。

THE KINDS AND ACTIVITY OF CELL WALL DEGRADING ENZYMES PRODUCED FROM CORN STALK ROT PATHOGENS

A series of cell wall degrading enzymes (CWDEs) including pectin methylesterase(PE),polygalacturonase(PG), polymethylgalacturonase (PMG), polygalacturonic acid trans-eliminase(PGTE),pectin methyl trans-eliminase(PMTE)and Cx were found in corn stalk pathogens,Pythium aphanidermatum and Fusarium graminearum.CWDEs produced from F.graminearum showed higher activities as compared with those from P.aphanidermatum.There were much difference of enzyme activities between in vitro and in vivo CWDEs.Results from enzyme dynamics analysis showed that different kinds of CWDEs had special optimum temperature,pH and reaction time of their maximum activities.For example,PG,PMG and Cx as a hydrolytic enzymes showed maximum activities at pH 6.0,5.0,6.0 and 50℃,40℃,50℃;PGTE and PMTE as a lytic enzymes at pH 9.0,9.0 and 30℃,20℃,respectively.