Keynote Speaker

Prof. Ya-Wen He

Prof. Ya-Wen He

State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
Speech Title: The Phytopathogen Xanthomonas Employs the RND Family Pump HepABCD for SA and Phenolic Acid Efflux and Enhancing Viability and Antioxidant Activity

Abstract: Xanthomonas is one of the most widespread and destructive bacterial plant pathogens, posing a significant threat to global food security. Xanthomonas pathovars exhibit remarkable host specificity and adaptability, and are capable of infecting a variety of staple crops, including rice, citrus, and tomato. Xanthomonas campestris pv. campestris (Xcc) is the causal pathogen of black rot in cruciferous plants. Upon infection, Xcc triggers the accumulation of salicylic acid (SA) and a range of other phenolic acids in the host plants. The mechanism by which Xcc copes with these defense signal and compounds remains unclear. Here, we revealed that Xcc senses SA and these phenolic acids via HepR. After sensing, Xcc exports SA, benzoic acid, cinnamic acid, and their monohydroxylated derivatives through the resistance-nodulation-division family efflux pump HepABCD. This efflux system influenced glutathione and catalase levels in the wild-type strain XC1, affecting cell viability and modulating ROS levels. We identified HepR as a sensor for SA and 4-hydroxybenzoic acid (4-HBA). The tryptophan residue W22 is critical for HepR binding to SA and 4-HBA. Binding of SA and 4-HBA caused HepR to dissociate from its promoter Phep and induced hepABCD expression. Additionally, HepR acts as a redox sensor, and cysteine-to-serine mutations at C39 or C77 significantly reduced its binding affinity to Phep. Collectively, these findings highlight the crucial role of phenolic acid sensing and efflux in Xcc viability and host colonization.


Biography: Prof. Dr. Ya-Wen He is a tenured Professor of Life Sciences and Biotechnology at Shanghai Jiao Tong University with expertise in microbial quorum sensing, plant protection, and synthetic biology of xanthan gum and biopesticide, especially in the field of quorum sensing of plant pathogens Xanthomonas. He has studied and worked in China, Singapore, and USA. He has authored over 150 peer-reviewed journal articles, contributed 5 invited book chapters, and edited two books. Prof. He is an active member of five editorial boards. His work is widely cited (over 5,000 citations; h-index >50) and recognized globally.