Control Effect And Mechanism Of Bacillus Amyloliquefaciens 41B-1 On Sclerotium Rolfsii

Sclerotium rolfsii is a kind of soil borne fungal disease.In recent years,Sclerotium rolfsii has seriously threatened the production of peanut(Arachis hypogaea)in China.The host of the disease is widespread and can survive in the soil in the form of micro sclerotia for a long time.The control effects of disease resistance breeding,chemical control,and crop rotation are not ideal,and prevention and control are difficult.Endophytes of plants have played a role in biological control of bacterial diseases,fungal diseases,and nematode diseases.Endophytes of plants have unique advantages in the prevention and control of plant-borne diseases,and are considered to be natural resource bacteria used for biological control of plant diseases,especially plant diseases that are difficult to control chemically.Bacillus amyloliquefaciens 41B-1 is a biocontrol bacterium with antagonistic activity against Sclerotium rolfsii.In this study,Sclerotium rolfsii as indicator bacteria to explore the mechanism of resistance strain 41B-1.The morphology of mycelia and cells were observed by the plate confrontation test,and the ability of 41B-1 to produce the enzyme was studied.The mechanism of antagonizing the disease was also explored by measuring the expression of resistance-related genes in peanut.In order to improve the fermentation production level of antagonistic 41B-1,the optimum fermentation level of 41B-1 was obtained by selecting different fermentation time,fermentation temperature,initial pH,inoculation quantity and rotational speed.The 41B-1 fermented liquid and white carbon black were used to make powder.The dynamic changes of the strain of the powder containing the antagonistic 41B-1 in 6 months were investigated and the safety of the powder was evaluated.The prepared antibacterial 41 B-1 containing powder was used in the greenhouse and in the field to test its efficacy.t was found that the dosage form had better control effect on Sclerotium rolfsii.The main results of this paper are as follows:1.in the test of 41B-1 and Sclerotium rolfsii plate confrontation,it can cause swollen distortion,mycelial growth distortion,cell wall damage,and intracellular substance leakage.41B-1 has the ability to produce cellulase,pectinase,xylanase,amylase and protease.2.41B-1 can induce hydrogen peroxide outburst and callose deposition in peanut leaves,resulting in a strong immune response in peanut plants.After inoculation with antagonistic bacteria 41B-1,peanut disease-associated protein 10(ARPR10),ADP ribosylation factor(ARF),zinc finger protein(ZF),14-3-3 protein and RUB 1 binding enzyme(RCE)in disease resistance and anti-oxidation genes showed up-regulation to varying degrees.3.In fermentation single factor tests,the optimal fermentation level of antagonistic bacteria 41B-1 was determined:fermentation time 48 h,fermentation temperature 370C,initial pH 7,inoculum volume 4%,shaker speed 150 r/min,and the bacteriostasis effect of the antagonistic 41B-1 was best under this condition.4.with white carbon black as the carrier to make the powder containing the antagonistic 41B-1,the bacteria can maintain a stable level in 6 months,and still have the amount of 8.5×107cfu/g in sixth months.The safety identification of 41B-1 wettable powder has no effect on the germination,emergence rate and growth of peanut seeds.It is proved that the wet powder of Bacillus amylobacilli 41B-1 is safe for the growth of peanut.5.Greenhouse and field control experiments were performed on white carbon black powders containing antagonistic bacteria 41B-1.The results showed that the control effect was best and the control effect was 33.90%when the suspended seed was soaked in the greenhouse with a mass ratio of 1:100.In field trials,50 times dilution of powder had the best control effect and the control effect was 57.41%.