Screening And Application Of Tobacco Antagonistic Endophytic Bacteria Against Phytophthora Parasitica Var. Nicotianae

Endophytic bacterium lived in the plant, and prevented and controlled the plant disease by producing secondary metabolic substances, inducing plant system resistant, promoting plant growth, and occupying ecological spaces, etc. The study made use of endophytic bacterium against tobacco black shank.From healthy tobaccos in heavy disease field of tobacco black shank , 298 endophytic bacterium strains were isolated in Yongzhou and Hunan Angriculture University, etc. Three antagonistic bacterium, HN4, YN2 and XY25 showed a clear antagonism effect against Phytophthora parasitica var. nicotianae by confront cultivation , which reached 66.15%, 70.35% and 69. 25%. In greenhouse, They had good preventing and controlling effects as 47. 78%, 60. 95% and 70. 53% respectively. Especially the effect of XY25 of the efficacy trials is beyond 70%. According to the physiological and biochemical characteristics, the bacteria strains HN4, YN2 and XY25 were identified as Pseudomonas fluorescence , Bacillus subtil is and Bacillus cereus.The study of antagonistic mechanism of three strains showed: three endophytic bacterium strains could inhibit hypha growth and germination of the zoospores of Phytophthora parasitica var. nicotianae. Inoculated the plants of tobacco, YN2 and XY25 also induced Phytophthora parasitica var. nicotianae resistances in the plants as they induced higher activity variety of PPO, PAL and PO significantly. The colonization of tobacco endophytic bacterium with the label of rifampin and fungi revealed: after...