食线虫真菌椭圆单顶孢的菌寄生作用及其生化机制  

Mycoparasitism of Nematode-trapping Fungus Monacrosporium ellipsosporum and Its Biochemical Basis

作　　者：马桂珍[1] 李世东[1] 谢丙炎[2] 吕国忠[3] 

机构地区：[1]中国农业科学院生物防治研究所,北京100081 [2]中国农业科学院蔬菜花卉研究所,北京100081 [3]沈阳农业大学,沈阳110161

出　　处：《中国农业科学》2004年第3期370-375,共6页Scientia Agricultura Sinica

基　　金：国家"863"计划资助项目(2001AA246011)

摘　　要：用核盘菌(Sclerotinia sclerotiorum)菌核作诱饵,从云南省玉溪市一烟草田土壤中分离获得了1株捕食线虫丝孢菌,经鉴定为椭圆单顶孢[Monacrosporium ellipsosporum (Preuss) Cooke & Dickinson]。该菌在自然土壤中对核盘菌菌核的定殖率为18%,人工回接对菌核的侵染率为32%。对峙培养结果表明,该菌与核盘菌和立枯丝核菌(Rhizoctonia solani)菌落之间不形成抑菌带,表明该菌对后2种病菌的营养竞争作用较弱和无抗生作用参与。但该菌可在后两者菌落上生长,并显著抑制其生长。扫描电镜和光学显微镜观察可见,该菌菌丝紧贴核盘菌菌丝上,并与其并行生长;在立枯丝核菌菌丝上形成弹簧状菌丝圈缠绕。对真菌细胞壁降解酶活性测定结果表明,在马铃薯葡萄糖液体培养中,该菌蛋白酶活性为81.3±7.6 U,未检测到总几丁质酶、外切几丁质酶和β-1,3-葡聚糖酶活性。几丁质和菌核研碎物可诱导该菌产生几丁质酶、葡聚糖酶。在几丁质琼脂培养基平板上产生明显的水解透明圈。在以核盘菌菌核研碎物为营养源的液体培养基中培养4d后,总几丁质酶、外切几丁质酶、β-1,3-葡聚糖酶和蛋白酶活性分别为140.2±11.9、82.9±4.1、111.2±7.6和76.1±4.3 U,表明这些酶类在菌寄生过程中可能具有重要作用。Monacrosporium ellipsosporum, a typical nematode-trapping fungus, was isolated by baiting with sclerotiaof Sclerotinia sclerotiorum in soil from a tobacco field in Yuxi, Yunnan Province. Colonization frequency of the fungus onthe sclerotia was 18% in natural soil. Reinoculation tests by placing surface-sterilized sclerotia on colony of the fungus for2 weeks and then surface-sterilized again led to 32% sclerotia infected. Dual culture tests in PDA plates did not give rise toa suppression zone between the colonies of M. ellipsosporum and its counterpart fungi S. sclerotiorum and Rhizoctoniasolani,suggesting no or weak nutritional competition and antifungal compounds involved. However, M. ellipsosporumcould grow over the colonies of the S. sclerotiorum or R. solani, and significantly inhibit their growth on agar plates.Scanning electronic and light microscopic observations showed that hyphae of M. ellipsosporum grew along and oppressedon hyphae of S. seclerotiorum and coiled around hyphae of R. solani with spring-like structure. Bioassay of cell wall-degrading enzymes showed that the M. ellipsosporum grew well in chitin agar plates, resulting in clear transparent hydrolysiszone. Activities of total chitinase, exo-chitinase,β-1,3-glucanase and protease were 140.2±11.9,82.9±4.1,111.2±7.6 and 76.1±4.3 U, respectively, after incubation for 4 days at 30 oC in liquid medium containing ground sclerotia of S.selerotiorum as sole nutrient resource. It is suggested that these enzymes might be important for the mycoparasitism of M.ellipsosporum.

关 键 词：捕食线虫真菌 椭圆单顶孢 菌寄生作用 生化机制 细胞壁降解酶 寄生线虫 天敌 土壤真菌 

分 类 号：S476[农业科学—农业昆虫与害虫防治]