Publications (25) View all
-
Article: Layered pattern receptor signaling via ethylene and endogenous elicitor peptides during Arabidopsis immunity to bacterial infection.
[show abstract] [hide abstract]
ABSTRACT: Recognition of molecular patterns characteristic of microbes or altered-self leads to immune activation in multicellular eukaryotes. In Arabidopsis thaliana, the leucine-rich-repeat receptor kinases FLAGELLIN-SENSING2 (FLS2) and EF-TU RECEPTOR (EFR) recognize bacterial flagellin and elongation factor EF-Tu (and their elicitor-active epitopes flg22 and elf18), respectively. Likewise, PEP1 RECEPTOR1 (PEPR1) and PEPR2 recognize the elicitor-active Pep epitopes conserved in Arabidopsis ELICITOR PEPTIDE PRECURSORs (PROPEPs). Here we reveal that loss of ETHYLENE-INSENSITIVE2 (EIN2), a master signaling regulator of the phytohormone ethylene (ET), lowers sensitivity to both elf18 and flg22 in different defense-related outputs. Remarkably, in contrast to a large decrease in FLS2 expression, EFR expression and receptor accumulation remain unaffected in ein2 plants. Genome-wide transcriptome profiling has uncovered an inventory of EIN2-dependent and EFR-regulated genes. This dataset highlights important aspects of how ET modulates EFR-triggered immunity: the potentiation of salicylate-based immunity and the repression of a jasmonate-related branch. EFR requires ET signaling components for PROPEP2 activation but not for PROPEP3 activation, pointing to both ET-dependent and -independent engagement of the PEPR pathway during EFR-triggered immunity. Moreover, PEPR activation compensates the ein2 defects for a subset of EFR-regulated genes. Accordingly, ein2 pepr1 pepr2 plants exhibit additive defects in EFR-triggered antibacterial immunity, compared with ein2 or pepr1 pepr2 plants. Our findings suggest that the PEPR pathway not only mediates ET signaling but also compensates for its absence in enhancing plant immunity.Proceedings of the National Academy of Sciences 02/2013; · 9.68 Impact Factor -
Article: Arabidopsis COP1/SPA1 complex and FHY1/FHY3 associate with distinct phosphorylated forms of phytochrome A in balancing light signaling.
[show abstract] [hide abstract]
ABSTRACT: Fine tuning of light signaling is crucial to plant development. Following light-triggered nuclear translocation, the photoreceptor phytochrome A (phyA) regulates gene expression under continuous far-red light and is rapidly destabilized upon red light irradiation by E3 ubiquitin ligases, including COP1. Here we provide evidence that the light signaling repressors SPA proteins contribute to COP1-mediated phyA degradation and that a COP1/SPA1 protein complex is tightly associated with phyA ubiquitination activity. Furthermore, a phosphorylated phyA form accumulates in the nucleus and preferentially associates with the COP1/SPA1 complex. In contrast, underphosphorylated phyA predominantly associates with the phyA-signaling intermediates FHY3 and FHY1. However, COP1 associates with underphosphorylated phyA in the absence of FHY3 or FHY1, suggesting that phyA associations with FHY3 and FHY1 protect underphosphorylated phyA from being recognized by the COP1/SPA complex. We propose that light-induced phyA phosphorylation acts as a switch controlling differential interactions of the photoreceptor with signal propagation or attenuation machineries.Molecular cell 09/2008; 31(4):607-13. · 14.61 Impact Factor -
Article: A Ca(2+)-dependent protein kinase that endows rice plants with cold- and salt-stress tolerance functions in vascular bundles.
[show abstract] [hide abstract]
ABSTRACT: A rice Ca(2+)-dependent protein kinase, OsCDPK7, is a positive regulator commonly involved in the tolerance to cold and salt/drought. We carried out in situ detection of the transcript and immunolocalization of the protein. In the wild-type rice plants under both stress conditions, OsCDPK7 was expressed predominantly in vascular tissues of crowns and roots, vascular bundles and central cylinder, respectively, where water stress occurs most severely. This enzyme was also expressed in the peripheral cylinder of crown vascular bundles and root sclerenchyma. Similar localization patterns with stronger signals were observed in stress-tolerant OsCDPK7 over-expressing transformants with the cauliflower mosaic virus 35S promoter. The transcript of a putative target gene of the OsCDPK7 signaling pathway, rab16A, was also detected essentially in the same tissues upon salt stress, suggesting that the OsCDPK7 pathway operates predominantly in these regions. We propose that the use of the 35S promoter fortuitously strengthened the localized expression of OsCDPK7, resulting in enhancement of the stress signaling in the inherently operating regions leading to improved stress tolerance.Plant and Cell Physiology 12/2001; 42(11):1228-33. · 4.70 Impact Factor -
Article: Receptor quality control in the endoplasmic reticulum for plant innate immunity.
[show abstract] [hide abstract]
ABSTRACT: Pattern recognition receptors in eukaryotes initiate defence responses on detection of microbe-associated molecular patterns shared by many microbe species. The Leu-rich repeat receptor-like kinases FLS2 and EFR recognize the bacterial epitopes flg22 and elf18, derived from flagellin and elongation factor-Tu, respectively. We describe Arabidopsis 'priority in sweet life' (psl) mutants that show de-repressed anthocyanin accumulation in the presence of elf18. EFR accumulation and signalling, but not of FLS2, are impaired in psl1, psl2, and stt3a plants. PSL1 and PSL2, respectively, encode calreticulin3 (CRT3) and UDP-glucose:glycoprotein glycosyltransferase that act in concert with STT3A-containing oligosaccharyltransferase complex in an N-glycosylation pathway in the endoplasmic reticulum. However, EFR-signalling function is impaired in weak psl1 alleles despite its normal accumulation, thereby uncoupling EFR abundance control from quality control. Furthermore, salicylic acid-induced, but EFR-independent defence is weakened in psl2 and stt3a plants, indicating the existence of another client protein than EFR for this immune response. Our findings suggest a critical and selective function of N-glycosylation for different layers of plant immunity, likely through quality control of membrane-localized regulators.The EMBO Journal 09/2009; 28(21):3439-49. · 9.20 Impact Factor -
Article: Manipulation of the eukaryotic transcriptional machinery by bacterial pathogens.
[show abstract] [hide abstract]
ABSTRACT: Pathogenic bacteria inject a diverse set of effectors into eukaryotic host cells and manipulate the cellular environment to enhance bacterial fitness. There is mounting evidence that the transcription machinery in the nucleus of plant cells is a target of various bacterial effectors. These effectors seem to mimic the actions of host nuclear components. To monitor and counteract such virulence-promoting strategies, plants have acquired unique immune-sensing mechanisms.Cell host & microbe 09/2008; 4(2):96-9. · 13.02 Impact Factor
