Salicylic acid biosynthesis and metabolism in plant-microbe interactions

Abstract

Salicylic acid （SA） is a phenolic compound that has been recognized as a plant hormone, playing a key role in the activation of defense responses after pathogen infection.　Two SA biosynthesis pathways have been proposed in plants; one via phenylalanine and the other via isochorismic acid.　Once plants synthesize SA to activate defense response, most of SA can be converted to SA metabolites.　These SA metabolites may have distinct roles in plants, such as inactivation of SA signaling and long distance propagation of defense signaling.　In addition, some plant pathogens can modulate host SA biosynthesis pathway by enzymatic effectors that metabolize SA precursors leading to less SA accumulation.　As SA is a critical component in plant immunity, disrupting SA biosynthesis can be a common infection strategy for plant pathogens.　Here we review our current knowledge and recent progress on the biosynthesis and metabolism of SA during plant-microbe interactions.