A human pathogenic bacteriumShigellaproliferates in the plant through the adoption of type III effectors for Shigellosis

Human enteropathogenic bacteria has been reported to be transmitted by fresh vegitables. Shigella , which infects primates, is reportedly transmitted by fresh vegetables; however, its molecular interactions with plants have not been elucidated. Here, we show that four Shigella strains, S. boydii ( S. b ), S. sonnei , S. flexneri 2a ( S. f 2a), and S. flexneri 5a ( S. f 5a), proliferated at different levels in Arabidopsis thaliana . Microscopic studies revealed that these bacteria were present inside leaves and damaged plant cells. Green fluorescent protein (GFP)-tagged S. b and S. f 5a colonized in leaves only, and S. f 2a colonized both leaves and roots. Using mutants lacking type III secretion systems (T3SS), we found that T3SS of Shigella that regulate the pathogenesis of Shigellosis in humans also play a central role in proliferation in Arabidopsis. Strikingly, the immunosuppressive activity of two T3S effectors, OspF and OspG, were needed for the proliferation of Shigella in Arabidopsis . Of note, delivery of OspF or OspG effectors inside of plant cells upon Shigella inoculation was confirmed by using a split GFP system, respectively. These findings demonstrate that the human pathogen Shigella can proliferate in plants by adoption of immunosuppressive machinery for its original host human.