7th joint conference "Joint Microbiology & Infection Conference 2024" of the DGHM and VAAM

Abstract: Pathogenicity of most Gram-negative human and plant pathogenic bacteria depends on a type III secretion (T3S) system which injects effector proteins (T3Es) into the eukaryotic cell. We study the interaction between Xanthomonas euvesicatoria and its host plants pepper and tomato. The bacteria enter plant tissues via natural openings (stomata) or wounds and settle down in the intercellular spaces. This intimate contact induces expression of the bacterial T3S system, a nanomachine spanning both bacterial membranes, prolonged by a T3S pilus, a thin and hollow structure (in animal pathogens corresponding to the needle). The Xanthomonas T3S system injects more than 30 different T3Es into the plant cell, termed Avr (avirulence protein), if they were identified before the discovery of the T3S system, or Xop (Xanthomonas outer protein). The outcome of an infection depends on the genotype of both the plant and the bacterium. In susceptible plants, T3Es interfere with host cell processes to the benefit of the pathogen and allow its proliferation. In a resistant plant, a plant resistance gene mediates recognition of a “corresponding” T3E, often resulting in a hypersensitive response (HR), a rapid and localized programmed cell death restricting pathogen multiplication. T3Es from Xanthomonas exhibit different biochemical activities, e.g., as plant immunity suppressors, cell death inducers, ubiquitin ligase or transcription factor. Selected T3Es will be discussed.

How a plant pathogenic bacterium manipulates the plant

Franconia Saal (Plenary Hall)

Ulla Bonas

Plenary Speaker