Study On The Physiological Races Of Setosphaeira Turcica And Its Biocontrol Reseach By Chaetomium Globosum

Abstract: Northern Corn Leaf Blight caused by Exserohilum turcicum(Pass.) Leonard&Suggs (teleomorph=Setosphaeriaturcica (Luttrell) Leonard&Suggs; syn.=Helminthosporium turcicum), is an important foliar disease of corn (Zea mays L.) that occursthroughout the world virtually everywhere corn is grown. In China, it is one of thepredominant diseases of corn in parts of the southwest and northeast, resulting in huge20%to50%economic losses and this pose a serious threat to maize production.In the prevention andcontrol of northern corn leaf blight, breeding for disease resistance corn and theimplementation of chemical fungicide is the most efficient method. But a long time ofbreeding resistance corn, may lead to the emergence of new resistance genes and thus willexacerbate the physiological differentiation of S. turcica. Chemical fungicides are notconducive to safe and sustainable environment-friendly development. Biological controlmethod should be taken to prevent and control NCLB.In this paper,32single conidial isolates of S. turcica were collected throughout JilinProvince.21inbred lines from the inbred collection were used to determine physiologicalraces. The strain No.05which has the strongest inhibitory effect agaist S. turcica wereselected from16endophytic fungi that were stored in the laboratory. Morphological andmolecular biological identification of the best anti-S. turcica activity strain No.05. Resistanceto E. turcicum activity of the secondary metabolites of No.05; Detect the efficacy ofchaetoglobosin A to S. turcica. Therefore, the results of this study are as follows:1. In2007-2009,32single conidial isolates of S. turcicawere collected throughoutJilinProvince.21inbred lines such as A619, A619Ht2, A632, A632Ht1, B37, B37Ht1,B37Ht3, B68, B68Ht1, B68HtN, B73, B73Ht1, Mo17, Mo17Ht1, Va26, Va26Ht1, Va26Ht2and Va26Ht3from the inbred collection were used to determine physiological races. With all32isolates the single genes resistance was very evident and all32isolates were race zero.There is no physiological races differences. 2. In this paper,16activity endophytic fungis were selected from many isolated strain fromhealthy ginkgo tissues and organs, and strain No.05suggested the most inhibition efficacy toS. turcica. The result is used to provide a theoretical basis on biological control of NCLB, andalso create new bio-fungicide.3. A strain, No.05, was isolated fromthe medicinal plant Ginkgo biloba, and identified asChaetomium globosum by morphology and molecular biology methods.4. In dual cultures on potato dextrose agar medium, this strain suppressed mycelial growthof numerous plant pathogenic fungi, especially that of S. turcica. Different concentration ofstrain No.05culture filtrates inhibited mycelial growth, conidial germination of S. turcica.Control of NCLB on detached maize leaves by different concentrations of culture filtrates ofChaetomium globosum strain No.05. Bioassay-guided chemical investigation by Gel filtrationchromatography, Silica gel column chromatography, Reversed phase column chromatographyand led to the isolation and purification of six active compounds from fermentation of strainNo.05and their structures were identified as chaetoglobosin A, C, D, E, G and R by means ofspectroscopic analysis(MS，1H，13C NMR and2D NMR).For the first time, the potent antifungal activity of chaetoglobosin A from endophytic fungiagainst phytopathogenic fungi S. turcica.The MIC and IC50for chaetoglobosin A on S.turcica mycelial growth is <0.1μg/ml and0.5729μg/ml, respectively. Control of NCLB ondetached maize leaves by different concentrations of chaetoglobosin A.Thus this provides thebasis and foundation for the next step for control of S. turcica.by C globosum No.05.