Antagonistic Activity Of Endophyte Streptomyces Rochei And Its Effect To Soil-borne Diseases Of Vegetables

Vegetables are important economic crops in China.Due to cultivation area expansion,species diversity,multiple cropping and cultivated technology,vegetable diseases occurring in kinds,frequency and extent were serious,becoming the important obstacle of sustainable development of the vegetable industry.Using antagonistic microorganisms or its metabolites substances for disease prevention and control are regarded as an ideal bio-control approach.The present subject screened a strain of endophyte of vegetable,Streptomyces rochei,and analyzed the antagonism to fungal disease of vegetables,to provide a reference for the control of vegetable fungal diseases.The main achievements were as follows:1.Screening and fermentation of endophytic actinomycetes,S.rochei.The endophytic actinomycetes were isolated from different tissues of cucumber seeding from the soil of fusarium wilt disease occurring.Isolating proportion of actinomycete from root,stem and leaf was 65.4%,23.1%and 11.5%respectively.Identification of a strain by morphological characters and 16S rDNA sequence showed it belonged to Streptomyces rochei.Fermentation medium was selected for S.rochei based on the nitrate and corn flour as the main C and N sources.Under submerge fermentation of 30-33 ℃,pH 7.0 at the start and 0.7 packing factor,metabolites of the strain were obtained by fermenting culture,with the bio-mass of endophytic actinomycetes up to 18 PMV(%).2.Analyzed the antagonism to fungal disease and metabolites of S.rochei.Antagonistic active test indicated that the isolated endophytic actinomycete strain S.rochei showed notably antifungal effect to 7 tested fungal pathogens,such as fusarium oxysporum,verticillium dahliae and b.cinerea,with the effect of EC50 between 27.54%and 398.25%.Culture media without of mycelium of S.rochei still showing inhibition to Fusarium oxysporum revealed that the stain could secret active metabolites.Three metabolites have been extracted from 9 polar components preliminarily,and two of them were identified as oxindole and benzoate.3.Tested the effect of endophytic actinomycetes,S.rochei to soil diseases of vegetable.Bio-assess and field test revealed the S.rochei was effect to several fungal diseases caused by soil-borne disease.The effects of seed coated with S.rochei in basin test to wilt disease,damping off and blight of cucumber were among 70.35%to 86.92%.Different treatments did different effect to damping off diseases of cucumber,tomato and pepper,with the treatment of seed coating>root dipping>root irrigation.Seeds coating with S.rochei also enhanced the yield of vegetables,the yield of tomato increased about 10.1%to 14.59%and 7.67%to 13.57%for pepper.