Abstract
Plants respond to pathogen infection using an innate immune system with at least two distinct recognition mechanisms. One mechanism recognizes microbe-associated molecular patterns (MAMPs). The other is resistance (R) gene-based surveillance system. In spite of importance of salicylic acid (SA) -mediated responses in R gene-mediated defense, it has been unclear if MAMP-triggered defense requires SA-mediated signaling mechanisms. Here we report intimate interactions between MAMP-triggered and SA-mediated signaling. We found that SA accumulated after treatments with a MAMP, flg22. Expression profile analysis revealed the importance of SA signaling in the MAMP-triggered gene expression change. Effects of flg22 pretreatment on resistance to a bacterial pathogen, Pseudomonas syringae pv. tomato DC3000 (PstDC3000), are partially dependent on SA signaling. These results indicate that the SA production triggered by flg22 is a component of the flg22-triggered signaling mechanism leading to resistance. We are currently studying signaling mechanisms involved in SA accumulation induced by flg22.
