Chloroplast-generated reactive oxygen species play a major role in localized cell death during the non-host interaction between tobacco and Xanthomonas campestris pv. vesicatoria

Authors

  • Matias D. Zurbriggen,

    1. Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
    Search for more papers by this author
  • Néstor Carrillo,

    1. Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
    Search for more papers by this author
  • Vanesa B. Tognetti,

    1. Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
    Search for more papers by this author
    • VIB Department of Plant Systems Biology, UGent, Technologie Park 927, B-9052 Gent, Belgium.

  • Michael Melzer,

    1. Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany
    Search for more papers by this author
  • Martin Peisker,

    1. Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany
    Search for more papers by this author
  • Bettina Hause,

    1. Leibniz-Institute of Plant Biochemistry, Weinberg 3, 06120 Halle (Saale), Germany
    Search for more papers by this author
  • Mohammad-Reza Hajirezaei

    Corresponding author
    1. Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
      (fax +49 39482 5515; e-mail mohammad@ipk-gatersleben.de).
    Search for more papers by this author

(fax +49 39482 5515; e-mail mohammad@ipk-gatersleben.de).

Summary

Attempted infection of plants by pathogens elicits a complex defensive response. In many non-host and incompatible host interactions it includes the induction of defence-associated genes and a form of localized cell death (LCD), purportedly designed to restrict pathogen advance, collectively known as the hypersensitive response (HR). It is preceded by an oxidative burst, generating reactive oxygen species (ROS) that are proposed to cue subsequent deployment of the HR, although neither the origin nor the precise role played by ROS in the execution of this response are completely understood. We used tobacco plants expressing cyanobacterial flavodoxin to address these questions. Flavodoxin is an electron shuttle present in prokaryotes and algae that, when expressed in chloroplasts, specifically prevents ROS formation in plastids during abiotic stress episodes. Infiltration of tobacco wild-type leaves with high titres of Xanthomonas campestris pv. vesicatoria (Xcv), a non-host pathogen, resulted in ROS accumulation in chloroplasts, followed by the appearance of localized lesions typical of the HR. In contrast, chloroplast ROS build-up and LCD were significantly reduced in Xcv-inoculated plants expressing plastid-targeted flavodoxin. Metabolic routes normally inhibited by pathogens were protected in the transformants, whereas other aspects of the HR, including the induction of defence-associated genes and synthesis of salicylic and jasmonic acid, proceeded as in inoculated wild-type plants. Therefore, ROS generated in chloroplasts during this non-host interaction are essential for the progress of LCD, but do not contribute to the induction of pathogenesis-related genes or other signalling components of the response.

Ancillary