Abstract
Summary Despite increasing incidences of human salmonellosis caused by consumption of contaminated vegetables, relatively little is known about how the plant immune system responds to and may inhibit Salmonella colonization. Here we show that S almonella T yphimurium activates the plant immune system primarily due to its recognition of the flg22 region in S almonella flagellin. Several previously identified plant genes that play a role in immunity were found to affect the host response to S almonella . The S almonella flg22 ( S eflg22) peptide induced the immune response in leaves which effectively restricted the growth of Salmonella as well as the plant pathogenic bacterium, P seudomonas syringae pv. tomato . Induction of immune responses by S eflg22 was dependent on the plant FLS 2 receptor. S almonella multiplied poorly on plant tissues similar to other bacteria which are non‐pathogenic to plants. However, S almonella populations increased significantly when co‐inoculated with P . syringae pv. tomato but not when co‐inoculated with a type III secretion system mutant of this pathogen. Our results suggest that S almonella benefits from the immune‐suppressing effects of plant pathogenic bacteria, and this growth enhancement may increase the risk of salmonellosis.