The Control Mechanisms Of Bacillus Subtilis BH-8 Against Tomato Grey Mould And Its Promoting Effect

Tomato grey mould caused by Botrytis cinerea,is one of the most severe diseases of tomato.Some problems,such as pesticides residue,environmental pollution,and pathogen resistance,have appeared recently because of relying on chemicals to control tomato grey mould for a long time.To develop environmental friendly bio-control agents is an effective way to alleviate these problems.A Bacilius subtilis strain BH-8 was isolated from rhizosphere soil samples with high antagonism effect against B.cinerea.Aiming at understanding the antifungal mechanism of BH-8 to B.cinerea,the control effect of BH-8 to tomato grey mould and the promoting effect of BH-8 to tomato,I did this work and got some results as follows:1.The conidial germination of B.cinerea were delayed,and hyphal growth were inhibited,and the hyphae become shorten,thicken,and darken after treatment by BH-8fermentation filtrate.Also,BH-8 fermentation filtrate has antagonistic activity to other 12kinds of pathogenic fungi,such as Colletotrichum lagenarium,Epicoccum nigrum,Alternaria alternata,Alternaria brassicae,etc.And the antagonistic effcects of BH-8 fermentation filtrate against C.lagenarium and A.alternata are best with the inhibition rate over 53%.2.The substances including proteins which can be extracted from BH-8 fermentation filtrate under 20%~90%saturation of ammonium sulfate have antifungal activities,and dissolve in water but slightly in organic solvents.And the antifungal activities of protein extracts under 30%saturation of ammonium sulfate is best.3.BH-8 strains have the ability of phosphate-solubilizing,and can secrete cellulase,protease,amylase,chitinase,siderophores and IAA in the dish.4.The activities of defense enzyme were enhanced in tomato induced by BH-8fermented liquid(1×10~8 cfu/mL).The activities of SOD,POD,CAT,and PAL in leaves increased significantly,and peaked among 12 to 24 hours.5.The defense response of tomato plant were induced by BH-8 fermented liquid,and the expressive quantity of defensive genes,for instance PR1?PR3?PDF?EIN2?CAT and PAL were significantly up-regulated and reached the peak at 12 or 24 hours after treatment by BH-8 fermented liquid.6.The control effects of BH-8 fermented liquid against tomato grey mould in the field were very well,and reached 82.25%in the field as the same with 80%procymidone 1000times diluent(87.14%).And the control effects of BH-8 fermented liquid 50 times dilution against tomato grey mould were 58.17%.7.The seed germination and seedling growth were promoted after treatment by BH-8fermented liquid.The germination percentage increased by 7.21%;the plant height increased by 22.15%,and the diameter of stem increased by 26.19%in the pot;the plant height increased by 19.35%,and the diameter of stem increased by 23.19%in the field.8.The compatibility of BH-8 and 50%Boscalid is well,50%Fludioxonil and 80%Procymidone are followed,40%Pyrimethanil is worser.