Design, Synthesis And Anti-citrus Huanglongbing Activity Of Amide Derivatives Containing 1,3,4-oxadiazole Sulfon

Citrus Huanglongbing disease is the most devastating disease in citrus production.In order to find the lead compounds with high activity against citrus Huanglongbing,this study spliced 1,3,4-oxadiazole and sulfone structures,introduced amides at different positions,and synthesized a series of amides containing 1,3,4-oxadiazole sulfone.Taking citrus Huanglongbing as the research object,the in vivo activity of the compounds was evaluated by real-time fluorescence quantitative method and the structure-activity relationship was analyzed.The mechanism of high activity compounds against citrus Huanglongbing was studied through transcriptome techniques.The work is summarized as follows:1.70 sulfonamides（amides）of 1,3,4-oxadiazolane were designed and synthesized.The structures of all target compounds have been characterized by ¹H NMR,¹³C NMR,and HRMS.2.Taking citrus Huanglongbing as the research object,the therapeutic activity of all target compounds against citrus Huanglongbing was tested.The test results showed that most of the target compounds had anti-citrus Huanglongbing activity to a certain extent,and compound C4 showed the best antibacterial activity.At 200 mg/L,the therapeutic activity against citrus Huanglongbing was 81.9%,significantly superior to the positive control penicillin（40.8%）and streptomycin（55.9%）.3.The results of citrus defense enzyme activity tests showed that compound C4significantly increased the activities of SOD and POD enzymes in citrus leaves at 200mg/L.4.Transcriptome gene sequencing analysis showed that the resistance differentially expressed genes in citrus were upregulated after treatment with compound C4.This indicates that compound C4 may enhance the defense response of citrus to the invasion of pathogenic bacteria,regulate the level of reactive oxygen species in plants to reduce plant damage,and enhance the disease resistance of citrus.