Study On Mutation Breeding Of Two Antagonistic Bacterium Strains Against Phytophthora Parasitica And Ralstonia Solanacearum

Tobacco black shank(Phytophthora parasitica) and tobacco bacterial blight (Ralstonia solanacearum) are the most serious diseases,except tobacco virus disease and tobacco brown spot in the loss extent of economy.Because the chem-control has large infection to it,Bio-control is an impromising way to control these tobacco diseases in many methods of disease-control.Bacillus spp.takes on potential disease-control remarkablely,which is an important part of preventing and curing plant diseases. Majority of Pseudomonas fluorescent strains are provided with the functions of promotion and resistion.The antagonistic bacteria of tobacco black shank and tobacco bacterial blight were screened and preliminary identify from soil samples in the rhizosphere of tobacco in Chongqing in this study.1 By screening antagonistic strains to Phytophthora nicotianae and Ralstonia solanacearum that were stored in lab,we obtained B-16-11 and P-71-2 which had better biocontrol effect as future mutant strains.The biocontrol effect of B-16-11 against Ralstonia solanacearum was 71.83%in greenhouse.The biocontrol effect of P-71-2 against Phytophthora arasitica and Ralstonia solanacearum respectively was 65.32% and 66.68%in greenhouse.2.Two barcterium strains was mutated by UV,Mw with the most optimum mutant time and concentration,When the light's power is 30W and the distance is 20 cm, Bacillus and Pseudomonas need 3 min UV strain;Bacillus and Pseudomonas need 3 min Mw strain;two barcterium strains was LiCl,we chose the concentration of LiCl, Bacillus need 0.4%and Pseudomonas need 0.6%.3 By the methods of UV,we obtained 8 forward mutation stains which the inhibition zone is more than14mm or the inhibition diameter is more than 28mm. Among them,the width of inhibition zone of UV-P17 against Phytophthora nicotianae respectively was 15.2mm and the inhibition diameter of UV-P17 against Ralstonia solanacearum was 28mm.The biocontrol effcet of UV-P17 against Phytophthora nicotianae was 78.7%in greenhouse.4 By the methods of microwave mutant,we obtained 12 forward mutation stains. Among them,the width of inhibition zone of Mw-P3,Mw-P44,Mw-P97 and Mw-P73 against Phytophthora nicotianae respectively were 15.2mm,15.8mm,15.4mm and 15.8mm.The inhibition diameter of Mw-B54 and Mw-P99 against Ralstonia solanacearum were 29mm.The biocontrol effcet of Mw-P44 and Mw-P73 against Phytophthora nicotianae were 76.9%and 71.6%in greenhouse.5 By the methods of UVL,we obtained 13 forward mutation stains.Among them, the width of inhibition zone of UVL-P9 against Phytophthora nicotianae respectively was 16mm.The inhibition diameter of UVL-P9 against Ralstonia solanacearum was 29mm.There is no bacter have forward mutation stain in the biocontrol in greenhouse.6 By the methods of MwL,we obtained 16 forward mutation stains.Among them, the width of inhibition zone of MwL-B108 and MwL-B73 against Rolstonia solanacearum respectively were 30mm.And the hibition zone of MwL-P26 against Phytophthora nicotianae and Rolstonia solanacearum was 15.3 mm and 29 mm.The biocontrol effcet of MwL-P77 against Phytophthora nicotianae was 84%,the biocontrol effect of MwL-B24 against Rolstonia solanacearum was 82.2%,the biocontrol effect of MwL-P26 and MwL-P53 against Rolstonia solanacearum and Phytophthora nicotianae were more than 68%.7 It has good exhibition in biocontrol in greenhouse and stabler which strained by the MwL.Successively cultured 14 times on plate,antagonism of mutant strains MwL-P53 was stabler than CK.The inhibition zone reached 13.2 mm after successively cultured 14 times and the inhibition diameter reached 28 mm after successively 10 times..