Salicylic Acid Signaling: Biosynthesis, Metabolism, and Crosstalk with Jasmonic Acid

Salicylic acid (SA) signaling plays an important role in local and systemic acquired resistance. Expression and activity of pathogenesis-related proteins are stimulated by the accumulation of SA, conferring resistance to pathogens. SA can be synthesized via the phenylpropanoid route or the isochorismate pathway and metabolized to form SA-glucoside and SA glucose-ester through glucosylation, and methyl salicylate through methylation. This summary focuses on genes involved in SA biosynthesis, metabolism, and signaling. SA and jasmonic acid (JA) crosstalk has an important role in regulating induced defense against pathogens by exerting antagonistic effects. Therefore, results on crosstalk between SA and JA are also shortly reviewed. Further investigation on the molecular aspect of SA and JA antagonism, elucidating how these pathways are linked to each other, and how they resolve the complexity of host-pathogen interaction will provide a better understanding on SA signaling and plant defense.