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POSTERS: Molecular/Cellular Plant‐Microbe Interactions I

P-369 - Xanthomonas euvesicatoria Xe4429 functions as an antitoxin, an expression repressor, and an enhancer of XeAvrRxo1 secretion

Monday, August 4, 2025
4:30 PM - 5:15 PM HST
Location: Exhibit Hall 3

    Presenting Author(s)

  • BZ

    Bingyu Zhao

    Professor
    Virginia Polytechnic Inst and State Univ
    Blacksburg, Virginia, United States

    • Author(s)

  • ZW

    Zhibo Wang

    Virginia Tech
    Blacksburg, Virginia, United States

  • QL

    Qi Li

    Virginia Polytechnic Institute and State University
    Blacksburg, Virginia, United States

  • TR

    Tiffany Roach

    Virginia Tech
    Blacksburg, Virginia, United States

  • AO

    Ayoyinka Okedigba

    Virginia Tech
    Blacksburg, Virginia, United States

  • cZ

    changhe Zhou

    Virginia Tech
    Blacksburg, Virginia, United States

  • FS

    Furong Sun

    Virginia Tech
    Blacksburg, Virginia, United States

  • DC

    Daniel Capelluto

    Virginia Tech
    Blacksburg, Virginia, United States

Abstract Text:

Xanthomonas euvesicatoria (Xe) is the causal agent of bacterial spot disease that threatens pepper and tomato production around the globe. X. euvesicatoria gene Xe4428 encodes a type III effector (T3E) that shares 89.67% amino acid identity with Xanthomonas oryzae pv. oryzicola (Xoc) T3E AvrRxo1. Thus far, the biological and biochemical functions of Xe4428 have not been characterized. Deletion of Xe4428 in the genome of X. euvesicatoria strain Xcv85-10 compromised its virulence to infect pepper and Nicotiana benthamiana plants. Transient co-expression of Xe4428 and Rxo1 on pepper and N. benthamiana plant leaves results in a robust hypersensitive reaction. Thus, Xe4428, renamed XeAvrRxo1, is a bona fide orthologue of XocAvrRxo1 with both virulence and avirulence functions. Expression of XeAvrRxo1 in X. euvesicatoria is toxic to the bacterial cells. Another X. euvesicatoria gene Xe4429, encodes a putative chaperone of XeAvrRxo1, which can interact with XeAvrRxo1 to suppress its toxicity in X. euvesicatoria. Xe4429 also binds to the promoter region of XeavrRxo1 and represses its transcription/translation in X. euvesicatoria bacterial cells. In addition, the expression of Xe4429 can enhance the secretion and translocation of XeAvrRxo1 into plant cells. Therefore, Xe4429 functions as an antitoxin, a transcription repressor, and a type III chaperone capable of enhancing the secretion and translocation of XeAvrRxo1 during pathogenesis.