Screening, Identification And Antagonism Of Antagonistic Organisms Against Phoma Wasabiae Yokogi And Their Biocontrol Efficiency

Wasabi is the main material of mustard's production, growing in Fuji in Japan and Ali Mountain in Taiwan, which is necessity of Japanese. And it is exported to American, Canada and Australia. So there is a large demand for it. According to recent abroad studies, scientists found wasabi has the functions of sterilization, protection from illness, antisepsis, diuresis, diaphoresis, clearing blood, whetting appetite, decreasing fat and intenerating blood vessel. Therefor, the need of wasabi is increasing and it is a farm produce which will bring great profits. Recent years wasabi has cropped largely in mainland of China, there are fields of wasabi in Qingcheng, Leshan, Mianyang Sichuan province. But its individual plant is infected by phoma wasabiae Yokogi. If the plants were infected, the production value would reduce more than 50%.In our study, soil samples were gathered from wasabi fields in Oingcheng Chengdu, from which 101 actinomyces strains and 57 bacterial strains were isolated by tube dilution assay. With phoma wasabiae Yokogi as the tested stain, 38 antibiotic actinomyces stains and 10 bacterial strains were screened out by hyphal extension inhibition assay. And with the best antibiosis against phoma wasabiae Yokogi, bacterium SA2 strain was resceened from these strains through aperture-strikeing method.Traditional phenotype classification, chemotaxonology, and moderm molecular taxonology were used to study the strain SA2. It was identified as Bacillus thuringiensis by morphological, cultural physiological, biochemical characteristics, and 16S rDNA sequences analysis.Because of good antibiosis against phoma wasabiae Yokogi, SA2, S11, S13, SA16 were used to control the disease in the potted plant. The tests exhibited that SA2 had the highest control efficacy. And the next field text of SA2 indicated that SA2 could control the disease and the control efficacy reached 78.98%. The antifungal strains in the study were well worth developing and applying for the biocontrol of the disease..