We carried out transcriptional profiling analysis in 10-d-old Arabidopsis thaliana seedlings treated with oligogalacturonides （OGs）, oligosaccharides derived from the plant cell wall, or the bacterial flagellin pept...We carried out transcriptional profiling analysis in 10-d-old Arabidopsis thaliana seedlings treated with oligogalacturonides （OGs）, oligosaccharides derived from the plant cell wall, or the bacterial flagellin peptide Fig22, general elicitors of the basal defense response in plants. Although detected by different receptors, both OGs and Fig22 trigger a fast and transient response that is both similar and comprehensive, and characterized by activation of early stages of multiple defense signaling pathways, particularly JA-associated processes. However, the response to Fig22 is stronger in both the number of genes differentially expressed and the amplitude of change. The magnitude of induction of individual genes is in both cases dose-dependent, but, even at very high concentrations, OGs do not induce a response that is as comprehensive as that seen with Fig22. While high doses of either microbe-associated molecular pattern （MAMP） elicit a late response that includes activation of senescence processes, SA-dependent secretory pathway genes and PR1 expres- sion are substantially induced only by Fig22. These results suggest a lower threshold for activation of early responses than for sustained or SA-mediated late defenses. Expression patterns of amino-cyclopropane-carboxylate synthase genes also implicate ethylene biosynthesis in regulation of the late innate immune response.展开更多
Intracellular Ca2＋ transients are an integral part of the signaling cascade during pathogen-associated molecular pattern （PAMP）-triggered immunity in plants. Yet, our knowledge about the spatial distribution of PAM...Intracellular Ca2＋ transients are an integral part of the signaling cascade during pathogen-associated molecular pattern （PAMP）-triggered immunity in plants. Yet, our knowledge about the spatial distribution of PAMP-induced Ca2＋ signals is limited. Investigation of cell- and tissue-specific properties of Ca2＋- dependent signaling processes requires versatile Ca2＋ reporters that are able to extract spatial information from cellular and subcellular structures, as well as from whole tissues over time periods from seconds to hours. Fluorescence-based reporters cover both a broad spatial and temporal range, which makes them ideally suited to study Ca2＋ signaling in living cells. In this study, we compared two fluorescence-based Ca2＋ sensors： the F6rster resonance energy transfer （FRET）-based reporter yellow cameleon NES-YC3.6 and the intensity-based sensor R-GECO1. We demonstrate that R-GECO1 exhibits a significantly increased signal change compared with ratiometric NES-YC3.6 in response to several stimuli. Due to its superior sensitivity, R-GECO1 is able to report fig22- and chitin-induced Ca2＋ signals on a cellular scale, which allowed identification of defined [Ca2＋]cyt oscillations in epidermal and guard cells in response to the fungal elicitor chitin. Moreover, we discovered that fig22- and chitin-induced Ca2＋ signals in the root initiate from the elongation zone.展开更多
文摘We carried out transcriptional profiling analysis in 10-d-old Arabidopsis thaliana seedlings treated with oligogalacturonides （OGs）, oligosaccharides derived from the plant cell wall, or the bacterial flagellin peptide Fig22, general elicitors of the basal defense response in plants. Although detected by different receptors, both OGs and Fig22 trigger a fast and transient response that is both similar and comprehensive, and characterized by activation of early stages of multiple defense signaling pathways, particularly JA-associated processes. However, the response to Fig22 is stronger in both the number of genes differentially expressed and the amplitude of change. The magnitude of induction of individual genes is in both cases dose-dependent, but, even at very high concentrations, OGs do not induce a response that is as comprehensive as that seen with Fig22. While high doses of either microbe-associated molecular pattern （MAMP） elicit a late response that includes activation of senescence processes, SA-dependent secretory pathway genes and PR1 expres- sion are substantially induced only by Fig22. These results suggest a lower threshold for activation of early responses than for sustained or SA-mediated late defenses. Expression patterns of amino-cyclopropane-carboxylate synthase genes also implicate ethylene biosynthesis in regulation of the late innate immune response.
文摘Intracellular Ca2＋ transients are an integral part of the signaling cascade during pathogen-associated molecular pattern （PAMP）-triggered immunity in plants. Yet, our knowledge about the spatial distribution of PAMP-induced Ca2＋ signals is limited. Investigation of cell- and tissue-specific properties of Ca2＋- dependent signaling processes requires versatile Ca2＋ reporters that are able to extract spatial information from cellular and subcellular structures, as well as from whole tissues over time periods from seconds to hours. Fluorescence-based reporters cover both a broad spatial and temporal range, which makes them ideally suited to study Ca2＋ signaling in living cells. In this study, we compared two fluorescence-based Ca2＋ sensors： the F6rster resonance energy transfer （FRET）-based reporter yellow cameleon NES-YC3.6 and the intensity-based sensor R-GECO1. We demonstrate that R-GECO1 exhibits a significantly increased signal change compared with ratiometric NES-YC3.6 in response to several stimuli. Due to its superior sensitivity, R-GECO1 is able to report fig22- and chitin-induced Ca2＋ signals on a cellular scale, which allowed identification of defined [Ca2＋]cyt oscillations in epidermal and guard cells in response to the fungal elicitor chitin. Moreover, we discovered that fig22- and chitin-induced Ca2＋ signals in the root initiate from the elongation zone.
