A marine bacterium elicits the type III secretion-dependent nonhost hypersensitive response in a land plant

ABSTRACT Active plant immune response involving programmed cell death called the hypersensitive response (HR) is elicited by microbial effectors delivered through the type III secretion system (T3SS). The marine bacterium Hahella chejuensis contains two T3SSs that are similar to those of animal pathogens, but elicited HR-like cell death in the land plant Nicotiana benthamiana , which was mediated by SGT1 and suppressed by AvrPto1. Thus, the land plant is capable of inducing the cell death in response to type III-secreted effectors of the marine bacterium it never have encountered, suggesting that plants may have evolved to cope with a potential threat posed by alien effectors. One-sentence summary A marine bacterium Hahella chejuensis harboring functional type III secretion systems induced nonhost hypersensitive response in a land plant Nicotiana benthamiana , which was mediated by SGT1 and suppressed by AvrPto1.