【摘要】 水稻纹枯病菌(Rhizoctonia solaniKühn)在改良的Marcus培养液中能产生多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)、果胶甲基半乳糖醛酸酶(PMG)、多聚半乳糖醛酸反式消除酶(PGTE)和果胶甲基反式消除酶(PMTE)5种胞壁降解酶,其中PG、Cx和PMG活性较高,而PGTE和PMTE活性很低。病菌产生胞壁降解酶的最佳条件是:在pH5培养液中28℃下静置培养6 d。病菌接种水稻叶鞘后也能显著产生PG、Cx和PMG等胞壁降解酶,并且病斑外侧褪绿部酶活最高,平均为对照(健康部)的3.4倍;其次是褐色部,酶活总量平均为对照的2.9倍;病斑中央枯白部酶活较低,但明显高于对照。这一结果提示,在病菌侵染和扩展过程中胞壁降解酶起重要作用。果胶酶(PG、PMG)和纤维素酶(Cx)无论是单独处理还是混合处理,对水稻叶鞘都具有显著地损伤细胞膜和浸渍组织的作用。更多还原

【Abstract】 The cell wall degrading enzymes(CWDEs) such as polygalacturonase(PG),cellulase(Cx),pectin methylgalacturonase(PMG),polygalacturonic acid trans-eliminase(PGTE) and pectin methyl trans-eliminase(PMTE) were produced in improved Marcus′s medium by Rhizoctonia solani Kühn causing rice sheath blight.Among five CWDEs,PG,Cx and PMG were significantly higher in the activity than PGTE and PMTE.The culture conditions for the CWDE production of the pathogen were studied.It was appropriate to the CWDE production for the pathogen to be cultured in improved(Marcus′s) medium(pH5) at 28 ℃ without shaking for six days.In addition,the pathogen could produce the CWGEs mentioned above in the lesion after inoculated to rice sheath.There were obvious differences in CWDE activity among three parts of the lesion such as outer chlorotic part,brown part and central dead part.The CWDE activity in the outer chlorotic part was the highest,which was about 3.4 times as much as that of control(healthy part).The next was the CWDE activity in the brown part,which was about 2.9 times as much as that of control.The CWDE activity in the central dead part was the lowest,but which was significantly higher than that of control.These results suggested that the CWDEs produced by the pathogen play an important role in lesion formation and expansion.The pectinase(PG,PMG) and cellulase(Cx) could damage the cell membrane of rice sheath and macerate the sheath tissue through single enzyme or mixed enzyme treatment.更多还原