Screening And Identification Of Antagonist Microbe Against Verticillium Wilt Of Cotton And The Antagonistic Mechanism Study

The purpose of this study is to separate and screen the antagonistic microorganism that can restrain verticillium wilt of cotton, to identify strain screened and to study the mechanism of antagonism, and to analysis the ITS region of Verticillium albo-atrum and V.dahliae's . The main results are as follows.1. 1723 strains were separated from the soil around the cotton root by the diluted plate method. 113 strains that are antagonistic to Verticillium dahliae were screened on the plate. The antagonistic effect on the plate,the effect of potted plant in greenhouse to control the cotton wilt disease and the broad-spectrum resistance were examined in 37 stains which are obviously antagonistic. The results show that 24 strains of 37 strains which are obviously antagonistic on the plate are resistant to cotton wilt disease in potted plant experiment.37 antagonistic strains have different broad-spectrum resistance.2. 3 bacterial strains which have obviously antagonistic effect were identified. The strain 112 was identified to be Bacillus megaterium according to morphology and physiological and biochemical trait. The strains 868 was identified to be Pseudomonas Fluorescens. The strain 312 was identified to be Bacillus cereus according to morphology, physiological and biochemical trait and 16SrDNA sequence analysis.3. The antagonistic microorganism of 3 bacterial strains which have obviously antagonistic effect was studied. The results show that the strain 112 and the strain 868 can not produce Siderophore and chitinase, but can produce secondary metabolite which have antibiosis. The result of the derivational systemic resistance experiment shows that the activity of the three defensive enzyme (i.e. POD, PPO and PAL) in cotton inoculated with three antagonistic strains enhanced, indicating that the antagonistic strains tested can induce systemic resistance in cotton.