Screening Of Antagonistic Bacillus Strains Against Pathogens Of Fusarium Dry Rot And Black Scurf In Potato And Its AFLP Analysis Of Genetic Diversity

Rhizosphere soil under potato plants of96plots in4different treatments of continuouscropping were sampled via five-sited sampling method in Tiaoshan farm, Jingtai County,Gansu province. AntagonisticBacillus strains against pathogens of Fusarium dry rot and blackscurf in potato were isolated and screened. AFLP techniques were used to analyze geneticdiversity of part of Bacillus strains. The results were as following:1. The soil samples were plated onto LB medium via dilution method for Bacillus strains,and625Bacillus strains were obtained from96potato plots. The results of statistical analysisindicated that the quantity of Bacillus strains tended to reduce with years’ increasing of potatocontinuous cropping, while tended to go up after6years’continuous cropping.2. The Bacillus strainsantagonistic to4pathogen isolates in3species (FusariumsolaniFSI, F. sambucinum FSM, RhizoctoniasolaniRS1、R. solani RS2) were screened by dual platemethod, and quantity of antagonistic Bacillus strains whose width of inhibition zone weregreater than2mm inclined to going down.3. The10Bacillus strains best antagonistic to4pathogens were screened by dual platemethod, and nonpathogenic to potato tubers were selected. The result showed the Bacillusstrains D1-0-1and D1-0-2do not leaded to rot of potato tubers, and the two strains wereidentified as B. atrophaeus via combination of physiological and biochemical characteristicsand gyrB gene sequences, it is the new record in Gansu province, China.4. The38Bacillus strainsantagonistic to4pathogen isolates in3species (FusariumsolaniFSI, F. sambucinum FSM, RhizoctoniasolaniRS1、 R. solani RS2) and respectivelyantagonistic to4pathogen and10Bacillus strains no antagonistic to4pathogen were selectedby width of inhibition zone to the pathogens above. AFLP techniques were used to analyzegenetic diversity of this Bacillus strains. DNA was extracted via reagent case method. Thegenomic DNA was double digested with enzymes EcoR Ⅰ and Mse Ⅰ,2primer pairsE-T/M-G、E-A/M-C were screened for selective amplification in this AFLP techniques based on their lighter, stable, and high polymorphic bands, while AFLP bands were much more andmore disperse under E-C/M-G, which was benefit for bands collection and data analysis.5.97loci in total with unambiguous amplified fragments were revealed2primer pairwith a number of polymorphic loci of87, a percentage of polymorphic loci of89.69%. Theresults of statistical analysis indicated that Bacillus strains of different antagonistic to4pathogen could divide into6variety refer to0.595ratio, which meant there were geneticdiversity among these strains that has different antagonistic to4pathogen in molecule level.6. The results of clustering dendrogram of Bacillus strains of different antagonistic to4pathogen analysis indicated that the classification of Bacillus strains has relation to itsantagonistic ability, but no relation to its antagonistic kind and source.