Preliminary Study On The Mechanism Of LJ02 Microbial Agent Against Cucumber Botrytis Cinerea

As one of the main vegetable crops in China,cucumber is increasingly affected by cucumber gray mold,which seriously affects crop yield.Bacillus amyloliquefaciens LJ02isolated in our laboratory is a biocontrol strain with antagonism and antagonism.In this experiment,cucumber was used as the host plant,and cucumber gray mold fungus was used as the target pathogen.The field was irrigated with bacterial suspensions of different dilution multiples of LJ02 for root control.The relationship between the endogenous condition and disease resistance of LJ02 was analyzed,and the effect on the endophytic bacteria in plants was analyzed preliminarily.The related resistance genes mediated by salicylic acid(SA)and ethylene(ET)pathway in roots and leaves were analyzed by RT-q PCR technology,and the resistance effect to cucumber gray mold was determined.Basic plant defense mechanisms.Transcriptome-based analysis provides a deeper understanding of the mechanisms of interaction.The following research results were obtained:(1)The field test of LJ02 diluted bacterial suspensions at different multiples found that when the 100-fold diluted bacterial suspension was applied,the disease prevention effect was the best,reaching 75%.Reached 70%,65%.(2)It was learned through root irrigation treatment and detection of the endogenous capacity of LJ02 at different time periods.The maximum endogenous amount was on the 10th day,the roots reached 5.590×10~6cfu/g,and the leaves 1.889×10~5cfu/g.It changes with time,and it shows a downward trend as a whole,and reaches the lowest value in 20 days.The root was 1.999×10~4 cfu/g,but the LJ02 strain was not detected in the leaves.(3)Preliminary understanding of the effects of LJ02 on other endophytes during the endogenous period.When the endogenous amount reached 10 days,LJ02 formed a dominant population in the roots and leaves of the plant,and no other microorganisms could be detected.The endogenous amount of LJ02 decreased,and the population of microorganisms increased slowly.(4)Analysis of the expression of disease resistance genes NPR-1,EIN-2,negative regulatory factor CTR-1,and receptor gene ETR-1 mediated by SA and ET pathway by RT-q PCR.LJ02 was found in cucumber During life,it can effectively activate the expression of NPR-1 resistance genes mediated by the SA pathway and the expression of EIN-2resistance genes mediated by the ET pathway.(5)The transcriptome high-throughput technology was used to analyze and predict the interaction between LJ02 and cucumber at different time periods.By analyzing the expression of differential genes,there were 158 differential genes in interaction with cucumber.Cytochrome P450(Cytochrome P450)protease plays an important role in promoting plant growth and inhibiting soil-borne diseases.In addition,the CUB85＿RS17715 gene was involved in L-serine synthesis through transcription analysis,and it also participated in stress response to the external environment.