Design and Synthesis of Mandelic Acid Derivatives for Suppression of Virulence T3SS against Citrus Canker.

Citrus canker, a highly contagious bacterial disease caused by subsp. (), poses a substantial threat to citrus crops, leading to serious reductions in fruit yield and economic losses. Most commonly used bactericides against lead to the rapid development of resistant subpopulations. Therefore, it is imperative to create novel drugs, such as type III secretion system (T3SS) inhibitors, that specifically target bacterial virulence factors rather than bacterial viability. In our study, we designed and synthesized a series of mandelic acid derivatives including 2-mercapto-1,3,4-thiazole. Seven substances were found to reduce the level of transcription of without affecting bacterial viability. bioassays indicated that compound significantly inhibited hypersensitive response and pathogenicity. RT-qPCR assays showed that compound visibly suppressed the expression of T3SS-related genes as well as citrus canker susceptibility gene . Furthermore, the combination with compound and quorum-quenching bacteria HN-8 can also obviously alleviate canker symptoms.