Salicylates  Salicylates including salicylic acid (SA) are major defense-signaling hormones (jasmonates are the others). Plants that are deficient in SA synthesis or signaling are much more susceptible to many microbial pathogens. SA accumulates upon pathogen infection, leading to the transcriptional induction of a very large number of disease associated genes. Many gaps remain in our understanding of this crucial but complex signaling pathway, but we are nearing a coherent picture of how SA works. SA also contributes to abiotic stress signaling, has roles in development, and is involved in the production of heat by certain plants including arum lilies. First posted February 28, 2011, revised by John Chandler ( August 14,