Transcytosis shuts the door for an unwanted guest

Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 3, D-72076 Tübingen, Germany. Electronic address: .
Trends in Plant Science (Impact Factor: 12.93). 07/2013; 18(11). DOI: 10.1016/j.tplants.2013.06.002
Source: PubMed


Penetration resistance is a well-described plant defense process, in which SOLUBLE N-ETHYLMALEIMIDE-SENSITIVE-FACTOR ATTACHMENT RECEPTOR (SNARE) proteins have essential roles in membrane fusion processes. Strong focal accumulation of these proteins at the site of attack by powdery mildew fungi has been considered important for their function. However, recent insight indicates that transcytosis, leading to the formation of exosomes, has an important role in this defense and, furthermore, that strong accumulation of these SNARE proteins with the exosomes is biologically irrelevant. These findings alter the established function of SNAREs in penetration resistance; therefore, in this opinion, we propose that PEN1 and its SNARE partners function on an endosome in their control of penetration resistance.

24 Reads
  • Source
    • "ara6 and pgm1 affect the proliferation of pathogenic bacteria Sugar treatment has been suggested to evoke a plant defense response represented by activation of the PATHOGENESIS RELATED 2 (PR2) gene (Thibaud et al. 2004). Membrane trafficking is involved in many aspects of plant defense responses (Hoefle and Huckelhoven 2008, Frei dit Frey and Robatzek 2009, Beck et al. 2012, Nielsen and Thordal-Christensen 2013, Inada and Ueda 2014). These lines of evidence prompted us to examine the effect of ara6 mutations on pathogenic bacterial infection . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Endosomal trafficking plays integral roles in various eukaryotic cell activities. In animal cells, a member of the RAB GTPase family, RAB5, is a key regulator of various endosomal functions. In addition to orthologs of animal RAB5, plants harbor the plant-specific RAB5 group, the ARA6 group, which is conserved in land plant lineages. In Arabidopsis thaliana, ARA6 and conventional RAB5 act in distinct endosomal trafficking pathways; ARA6 mediates trafficking from endosomes to the plasma membrane, whereas conventional RAB5 acts in endocytic and vacuolar trafficking pathways. ARA6 is also required for normal salt and osmotic stress tolerance, although the functional link between ARA6 and stress tolerance remains unclear. In this study, we investigated ARA6 function in stress tolerance by monitoring broad-scale changes in gene expression in the ara6 mutant. A comparison of the expression profiles between wild-type and ara6-1 plants revealed that the expression of the Qua-Quine Starch (QQS) gene was significantly affected by the ara6-1 mutation. QQS is involved in starch homeostasis, consistent with the starch content decreasing in the ara6 mutants to approximately 60% of that of the wild-type plant. In contrast, the free and total glucose content increased in the ara6 mutants. Moreover, the proliferation of Pseudomonas syringae pv. tomato DC3000 was repressed in ara6 mutants, which could be attributed to the elevated sugar content. These results suggest that ARA6 is responsible for starch and sugar homeostasis, most likely through the function of QQS. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For Permissions, please e-mail:
    Plant and Cell Physiology 02/2015; 56(6). DOI:10.1093/pcp/pcv029 · 4.93 Impact Factor
  • Source
    • "However, the exact role of SYP121 in penetration resistance is still unknown because papilla formation is not essential for penetration resistance (Nishimura et al. 2003), and SYP121 localizes not only to the PM but also in the paramural space at the fungal entry site (Meyer et al. 2009). Based on reports showing that SYP121 is also localized on the TGN, whereas its closest homolog SYP122, which cannot compensate for the loss of SYP121 in penetration resistance, is not (Drakakaki et al. 2012, Nielsen and Thordal- Christensen 2012), it is postulated that the role of SYP121 in penetration resistance is mediated by a function of endosomal SYP121 rather than by membrane fusion at the PM (Nielsen and Thordal-Christensen 2013). The specific activity of SYP121 at the endosomal compartments remains to be elucidated. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Membrane trafficking functions in the delivery of proteins that are newly synthesized in the endoplasmic reticulum (ER) to their final destinations, such as the plasma membrane (PM) and the vacuole, and in the internalization of extracellular components or PM-associated proteins for recycling or degradative regulation. These trafficking pathways play pivotal roles in the rapid responses to environmental stimuli such as challenges by microorganisms. In this review, we provide an overview of the current knowledge of plant membrane trafficking and its roles in plant-microbe interactions. Although there is little information regarding the mechanism of pathogenic modulation of plant membrane trafficking thus far, recent research has identified many membrane trafficking factors as possible targets of microbial modulation.
    Plant and Cell Physiology 03/2014; 55(4). DOI:10.1093/pcp/pcu046 · 4.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Plants respond to pathogen attack with dynamic rearrangements of the endomembrane system and rapid redirection of membrane traffic to facilitate effective host defence. Mounting evidence indicates the involvement of endocytic, secretory, and vacuolar trafficking pathways in immune receptor activation, signal transduction, and execution of multiple defence responses including programmed cell death (PCD). Autophagy is a conserved intracellular trafficking and degradation process and has been implicated in basal immunity as well as in some forms of immune receptor-mediated vacuolar cell death. However, the regulatory interplay of autophagy and other membrane trafficking pathways in PCD and defence responses remains obscure. This review therefore highlights recent advances in the understanding of autophagic and membrane trafficking during plant immunity, and discusses emerging molecular links and functional interconnections.
    Journal of Experimental Botany 01/2014; 65(5). DOI:10.1093/jxb/ert441 · 5.53 Impact Factor
Show more