哈茨木霉几丁质酶诱导及其对水稻纹枯病菌的拮抗作用

 在实验室条件下分别以几丁质和水稻纹枯病菌(Rhizoctonia solani)细胞壁作唯一碳源诱导哈茨木霉(Trichoderma harzianum)菌株NF9、TC3和P1产生几丁质酶,用硫酸铵沉淀法制备几丁质酶粗提液。上述木霉菌株内切几丁质酶活性(对胶体几丁质浑浊度的减少率)分别为79.8%、74.4%和76.0%,均显著高于非诱导的阳性对照。培养第5 d几丁质诱导的木霉菌株NF9和TC3内切几丁质酶活性显著高于由水稻纹枯病菌细胞壁诱导的酶活性。体外测定表明,通过诱导的木霉菌株TC3、NF9和P1几丁质酶粗提液对水稻纹枯病病菌的拮抗圈直径可达38、21和23 mm,与非诱导的阳性对照比较有显著性差异。对木霉几丁质酶拮抗作用的特点及生防应用进行了讨论。

Induced chitinases from Trichoderma harzianum strains and their antagonistic activity against rice sheath blight pathogen

The chitinases were induced from biocontrol agent Trichoderma harzianum strains NF9, TC3 and P1 by chitin or purified cell wall of Rhizoctonia solani ,the causal agent of rice sheath blight, as a sole carbon source under laboratory condition. The rough extracts of the chitinases were prepared by ammonium sulphate method. The induced endochitinase activity from the Trichoderma strains was measured as reduction percentage of the turbidity of colloidal chitin as 79.8%,74.4% and 76.0%, respectively, that was significantly higher than non induced control. The induced chitinase activity of strains NF9 and TC3 by chitin was significantly higher than that induced by the pathogen cell wall on the fifth day of the culture. The inhibition zone diameter by the chitinase extract from the strains TC3, NF9 and P1 was 38, 21 and 23 mm, respec tively, that was significantly increased comparing with the noninduced control. The parallel growth, coiling and parasitism of the T.harzianum hyphae on the pathogen hyphae was observed under SEM. The characteristics of the antagonism by chitinases from Trichoderma against fungal pathogens and their potential use for biocontrol are discussed.