title: Positive crosstalk of MAMP signaling pathways in rice cells.
abstract: Plants have evolved efficient defense mechanisms known as priming and synergy, both of which can mobilize defense responses more extensively against successive pathogen invasion or simultaneous stimulation by different signal molecules. However, the mechanisms underlying these phenomena were largely unknown. In the present study, we used cultured rice cells and combination of purified MAMP molecules as a model system to study the mechanisms of these phenomena. We found that the pretreatment of rice cells with a low concentration of bacterial lipopolysaccharide (LPS) apparently primed the defense responses induced by successive N-acetylchitooctaose (GN8) treatment. On the other hand, simultaneous treatment with GN8 and LPS also resulted in the similar enhancement of defense responses observed for the LPS-induced priming, indicating that the synergistic effects of these MAMPs are basically responsible for such enhancement of defense responses, though the effect could be interpreted as "priming" under some experimental conditions. These results also indicate that such a positive crosstalk of signaling cascade downstream of MAMP receptors seems to occur very rapidly, probably at early step(s) of signaling pathway. Comprehensive analysis of phytohormones revealed a specific enhancement of the synthesis of jasmonic acid (JA), both in the LPS pretreatment and also simultaneous treatment, indicating a role of JA in the enhancement of downstream responses.
authors.affiliation: Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Desaki
authors.forename: Ippei
authors.initials: I
authors.lastname: Otomo
authors.forename: Daijiro
authors.initials: D
authors.lastname: Kobayashi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Balakrishnan
authors.initials: B
authors.lastname: Venkatesh
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsuyumu
authors.forename: Hanae
authors.initials: H
authors.lastname: Kaku
authors.forename: Naoto
authors.initials: N
authors.lastname: Shibuya
mesh_terms: D002478:Cells, Cultured; D002686:Chitin / Q000276:immunology; D003517:Cyclopentanes / Q000276:immunology; D018506:Gene Expression Regulation, Plant; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology; D009844:Oligosaccharides / Q000276:immunology; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000276:immunology*; D054883:Oxylipins / Q000276:immunology; D010937:Plant Growth Regulators / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology*; D015398:Signal Transduction
chemical_list: D003517:Cyclopentanes; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D002686:Chitin; C082723:N-acetylchitooctaose; C011006:jasmonic acid