Publications (79) View all
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Article: Effector Biology of Plant-Associated Organisms: Concepts and Perspectives.
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ABSTRACT: Every plant is closely associated with a variety of living organisms. Therefore, deciphering how plants interact with mutualistic and parasitic organisms is essential for a comprehensive understanding of the biology of plants. The field of plant-biotic interactions has recently coalesced around an integrated model. Major classes of molecular players both from plants and their associated organisms have been revealed. These include cell surface and intracellular immune receptors of plants as well as apoplastic and host-cell-translocated (cytoplasmic) effectors of the invading organism. This article focuses on effectors, molecules secreted by plant-associated organisms that alter plant processes. Effectors have emerged as a central class of molecules in our integrated view of plant-microbe interactions. Their study has significantly contributed to advancing our knowledge of plant hormones, plant development, plant receptors, and epigenetics. Many pathogen effectors are extraordinary examples of biological innovation; they include some of the most remarkable proteins known to function inside plant cells. Here, we review some of the key concepts that have emerged from the study of the effectors of plant-associated organisms. In particular, we focus on how effectors function in plant tissues and discuss future perspectives in the field of effector biology.Cold Spring Harbor Symposia on Quantitative Biology 12/2012; -
Chapter: Basal Defence in Arabidopsis Against Pseudomonas syringae pv. phaseolicola : Beyond FLS2?
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ABSTRACT: We have developed a system to use natural variation between Arabidopsis ecotypes to study the basis of non-host/basal resistance. Our experiments suggest that the leucine rich repeat receptor kinase FLS2 and the flagellin perception system are at the core of this resistance mechanism. However, several genes/loci work in concert with FLS2 to specify non-host resistance in Arabidopsis to P.s. pv. phaseolicola race 6 1448A.12/2007: pages 91-95; -
Article: A new member of the Arabidopsis WRKY transcription factor family, AtWRKY6, is associated with both senescence- and defence-related processes.
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ABSTRACT: WRKY proteins constitute a large family of plant-specific transcription factors whose precise functions have yet to be elucidated. Here we show that expression of one representative in Arabidopsis, AtWRKY6, is influenced by several external and internal signals often involved in triggering senescence processes and plant defence responses. Progressive 5' deletions of the AtWRKY6 promoter allowed separation of defined regions responsible for the expression in distinct organs or upon pathogen challenge. Nuclear localization of AtWRKY6 was demonstrated; protein truncations and gain-of-function studies enabled delineation of a region harbouring a novel type of functional nuclear localization signal (NLS).The Plant Journal 11/2001; 28(2):123-33. · 6.16 Impact Factor -
Article: Patterns of plant subcellular responses to successful oomycete infections reveal differences in host cell reprogramming and endocytic trafficking.
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ABSTRACT: Adapted filamentous pathogens such as the oomycetes Hyaloperonospora arabidopsidis (Hpa) and Phytophthora infestans (Pi) project specialized hyphae, the haustoria, inside living host cells for the suppression of host defence and acquisition of nutrients. Accommodation of haustoria requires reorganization of the host cell and the biogenesis of a novel host cell membrane, the extrahaustorial membrane (EHM), which envelops the haustorium separating the host cell from the pathogen. Here, we applied live-cell imaging of fluorescent-tagged proteins labelling a variety of membrane compartments and investigated the subcellular changes associated with accommodating oomycete haustoria in Arabidopsis and N. benthamiana. Plasma membrane-resident proteins differentially localized to the EHM. Likewise, secretory vesicles and endosomal compartments surrounded Hpa and Pi haustoria revealing differences between these two oomycetes, and suggesting a role for vesicle trafficking pathways for the pathogen-controlled biogenesis of the EHM. The latter is supported by enhanced susceptibility of mutants in endosome-mediated trafficking regulators. These observations point at host subcellular defences and specialization of the EHM in a pathogen-specific manner. Defence-associated haustorial encasements, a double-layered membrane that grows around mature haustoria, were frequently observed in Hpa interactions. Intriguingly, all tested plant proteins accumulated at Hpa haustorial encasements suggesting the general recruitment of default vesicle trafficking pathways to defend pathogen access. Altogether, our results show common requirements of subcellular changes associated with oomycete biotrophy, and highlight differences between two oomycete pathogens in reprogramming host cell vesicle trafficking for haustoria accommodation. This provides a framework for further dissection of the pathogen-triggered reprogramming of host subcellular changes.Cellular Microbiology 01/2012; 14(5):682-97. · 5.46 Impact Factor -
Article: Receptor quality control in the endoplasmic reticulum for plant innate immunity.
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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
