Functions of pipecolic acid on induced resistance againstBotrytis cinereaandPseudomonas syringaepv.tomatoDC3000 in tomato plants

Amino acid metabolic pathways are involved in the plant immune system. Pipecolic acid (Pip), a lysine-derived non-protein amino acid, acts as an important regulator of disease resistance. Here, we report the functions of Pip on tomato disease resistance. Tomato seedlings treated with 0.5 mM Pip showed increased resistance toPstDC3000 andB. cinereacompared with the control. After pathogen infection, the expression of defence-related genes increased in plants pretreated with Pip, while reactive oxygen species (ROS) accumulation decreased. These data demonstrated that exogenous application of Pip induced resistance againstPstDC3000 andB. cinereain tomatoes, possibly through the regulation of ROS accumulation and defence-related gene expression.