DESVEAUX LAB

Category: Publications

  • The HopF family of Pseudomonas syringae type III secreted effectors

    The HopF family of Pseudomonas syringae type III secreted effectors

    Timothy Lo, Noushin Koulena, Derek Seto, David S. Guttman, and Darrell Desveaux

    Abstract

    Pseudomonas syringae is a bacterial phytopathogen that utilizes the type III secretion system to inject effector proteins into plant host cells. Pseudomonas syringae can infect a wide range of plant hosts, including agronomically important crops such as tomatoes and beans. The ability of P. syringae to infect such numerous hosts is caused, in part, by the diversity of effectors employed by this phytopathogen. Over 60 different effector families exist in P. syringae; one such family is HopF, which contains over 100 distinct alleles. Despite this diversity, research has focused on only two members of this family: HopF1 from P. syringae pathovar phaseolicola 1449B and HopF2 from P. syringae pathovar tomato DC3000. In this study, we review the research on HopF family members, including their host targets and molecular mechanisms of immunity suppression, and their enzymatic function. We also provide a phylogenetic analysis of this expanding effector family which provides a basis for a proposed nomenclature to guide future research. The extensive genetic diversity that exists within the HopF family presents a great opportunity to study how functional diversification on an effector family contributes to host specialization.

  • Expanded type III effector recognition by the ZAR1 NLR protein using ZED1-related kinases

    Expanded type III effector recognition by the ZAR1 NLR protein using ZED1-related kinases

    Derek Seto, Noushin Koulena, Timothy Lo, Alexandra Menna, David S. Guttman and Darrell Desveaux

    Abstract

    Nucleotide-binding domain and leucine-rich repeat domain containing (NLR) proteins are sentinels of plant immunity that monitor host proteins for perturbations induced by pathogenic effector proteins. Here we show that the Arabidopsis ZAR1 NLR protein requires the ZRK3 kinase to recognize the Pseudomonas syringae type III effector (T3E) HopF2a. These results support the hypothesis that ZAR1 associates with an expanded ZRK protein family to broaden its effector recognition spectrum.

  • Image-Based Quantification of Plant Immunity and Disease

    Image-Based Quantification of Plant Immunity and Disease

    Bradley Laflamme, Maggie Middleton, Timothy Lo, Darrell Desveaux, and David S. Guttman

    Abstract

    Measuring the extent and severity of disease is a critical component of plant pathology research and crop breeding. Unfortunately, existing visual scoring systems are qualitative, subjective, and the results are difficult to transfer between research groups, while existing quantitative methods can be quite laborious. Here, we present plant immunity and disease image-based quantification (PIDIQ), a quantitative, semi-automated system to rapidly and objectively measure disease symptoms in a biologically relevant context. PIDIQ applies an ImageJ-based macro to plant photos in order to distinguish healthy tissue from tissue that has yellowed due to disease. It can process a directory of images in an automated manner and report the relative ratios of healthy to diseased leaf area, thereby providing a quantitative measure of plant health that can be statistically compared with appropriate controls. We used the Arabidopsis thaliana–Pseudomonas syringae model system to show that PIDIQ is able to identify both enhanced plant health associated with effector-triggered immunity as well as elevated disease symptoms associated with effector-triggered susceptibility. Finally, we show that the quantitative results provided by PIDIQ correspond to those obtained via traditional in planta pathogen growth assays. PIDIQ provides a simple and effective means to nondestructively quantify disease from whole plants and we believe it will be equally effective for monitoring disease on excised leaves and stems.

  • A Mesoscale Abscisic Acid Hormone Interactome Reveals a Dynamic Signaling Landscape in Arabidopsis

    A Mesoscale Abscisic Acid Hormone Interactome Reveals a Dynamic Signaling Landscape in Arabidopsis

    We have defined a focused ABA signaling network of over 500 interactions among 138 proteins. The network can be queried functionally to define genes involved in ABA signaling. When merged with global expression patterns centered on abiotic stresses, the ABA network reveals specific modules related to each stress condition.

  • The type III effector HopF2Pto targets Arabidopsis RIN4 protein to promote Pseudomonas syringae virulence

    The type III effector HopF2Pto targets Arabidopsis RIN4 protein to promote Pseudomonas syringae virulence

    The type III effector HopF2Pto targets Arabidopsis RIN4 protein to promote Pseudomonas syringae virulence

    Wilton M, Subramaniam R, Elmore J, Felsensteiner C, Coaker G, Desveaux D

    Proc. Natl. Acad. Sci. U.S.A. 2010 Feb;107(5):2349-54

    PubMed PMID: 20133879

    Abstract

    Plant immunity can be induced by two major classes of pathogen-associated molecules. Pathogen- or microbe-associated molecular patterns (PAMPs or MAMPs) are conserved molecular components of microbes that serve as “non-self” features to induce PAMP-triggered immunity (PTI). Pathogen effector proteins used to promote virulence can also be recognized as “non-self” features or induce a “modified-self” state that can induce effector-triggered immunity (ETI). The Arabidopsis protein RIN4 plays an important role in both branches of plant immunity. Three unrelated type III secretion effector (TTSE) proteins from the phytopathogen Pseudomonas syringae, AvrRpm1, AvrRpt2, and AvrB, target RIN4, resulting in ETI that effectively restricts pathogen growth. However, no pathogenic advantage has been demonstrated for RIN4 manipulation by these TTSEs. Here, we show that the TTSE HopF2(Pto) also targets Arabidopsis RIN4. Transgenic plants conditionally expressing HopF2(Pto) were compromised for AvrRpt2-induced RIN4 modification and associated ETI. HopF2(Pto) interfered with AvrRpt2-induced RIN4 modification in vitro but not with AvrRpt2 activation, suggestive of RIN4 targeting by HopF2(Pto). In support of this hypothesis, HopF2 (Pto) interacted with RIN4 in vitro and in vivo. Unlike AvrRpm1, AvrRpt2, and AvrB, HopF2(Pto) did not induce ETI and instead promoted P. syringae growth in Arabidopsis. This virulence activity was not observed in plants genetically lacking RIN4. These data provide evidence that RIN4 is a major virulence target of HopF2(Pto) and that a pathogenic advantage can be conveyed by TTSEs that target RIN4.

  • Found in translation: high-throughput chemical screening in Arabidopsis thaliana identifies small molecules that reduce Fusarium head blight disease in wheat

    Found in translation: high-throughput chemical screening in Arabidopsis thaliana identifies small molecules that reduce Fusarium head blight disease in wheat

    Found in translation: high-throughput chemical screening in Arabidopsis thaliana identifies small molecules that reduce Fusarium head blight disease in wheat

    Schreiber KJ, Nasmith CG, Allard G, Singh J, Subramaniam R, Desveaux D

    Mol. Plant Microbe Interact. 2011 Jun;24(6):640-8

    PubMed PMID: 21303209

    Abstract

    Despite the tremendous economic impact of cereal crop pathogens such as the fungus Fusarium graminearum, the development of strategies for enhanced crop protection is hampered by complex host genetics and difficulties in performing high-throughput analyses. To bypass these challenges, we have developed an assay in which the interaction between F. graminearum and the model plant Arabidopsis thaliana is monitored in liquid media in 96-well plates. In this assay, fungal infection is associated with the development of dark lesion-like spots on the cotyledons of Arabidopsis seedlings by 4 days postinoculation. These symptoms can be alleviated by the application of known defense-activating small molecules and in previously described resistant host genetic backgrounds. Based on this infection phenotype, we conducted a small-scale chemical screen to identify small molecules that protect Arabidopsis seedlings from infection by F. graminearum. We identified sulfamethoxazole and the indole alkaloid gramine as compounds with strong protective activity in the liquid assay. Remarkably, these two chemicals also significantly reduced the severity of F. graminearum infection in wheat. As such, the Arabidopsis-based liquid assay represents a biologically relevant surrogate system for high-throughput studies of agriculturally important plant-pathogen interactions.

  • The Arabidopsis ZED1 pseudokinase is required for ZAR1-mediated immunity induced by the Pseudomonas syringae type III effector HopZ1a

    The Arabidopsis ZED1 pseudokinase is required for ZAR1-mediated immunity induced by the Pseudomonas syringae type III effector HopZ1a

    The Arabidopsis ZED1 pseudokinase is required for ZAR1-mediated immunity induced by the Pseudomonas syringae type III effector HopZ1a

    Lewis JD, Lee AH, Hassan JA, Wan J, Hurley B, Jhingree JR, Wang PW, Lo T, Youn JY, Guttman DS, Desveaux D

    Proc. Natl. Acad. Sci. U.S.A. 2013 Oct;:

    PubMed PMID: 24170858

    Abstract

    Plant and animal pathogenic bacteria can suppress host immunity by injecting type III secreted effector (T3SE) proteins into host cells. However, T3SEs can also elicit host immunity if the host has evolved a means to recognize the presence or activity of specific T3SEs. The diverse YopJ/HopZ/AvrRxv T3SE superfamily, which is found in both animal and plant pathogens, provides examples of T3SEs playing this dual role. The T3SE HopZ1a is an acetyltransferase carried by the phytopathogen Pseudomonas syringae that elicits effector-triggered immunity (ETI) when recognized in Arabidopsis thaliana by the nucleotide-binding leucine-rich repeat (NB-LRR) protein ZAR1. However, recognition of HopZ1a does not require any known ETI-related genes. Using a forward genetics approach, we identify a unique ETI-associated gene that is essential for ZAR1-mediated immunity. The hopZ-ETI-deficient1 (zed1) mutant is specifically impaired in the recognition of HopZ1a, but not the recognition of other unrelated T3SEs or in pattern recognition receptor (PRR)-triggered immunity. ZED1 directly interacts with both HopZ1a and ZAR1 and is acetylated on threonines 125 and 177 by HopZ1a. ZED1 is a nonfunctional kinase that forms part of small genomic cluster of kinases in Arabidopsis. We hypothesize that ZED1 acts as a decoy to lure HopZ1a to the ZAR1-resistance complex, resulting in ETI activation.

  • A bacterial acetyltransferase destroys plant microtubule networks and blocks secretion

    A bacterial acetyltransferase destroys plant microtubule networks and blocks secretion

    selected images from paper

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    A bacterial acetyltransferase destroys plant microtubule networks and blocks secretion

    Lee AH, Hurley B, Felsensteiner C, Yea C, Ckurshumova W, Bartetzko V, Wang PW, Quach V, Lewis JD, Liu YC, Börnke F, Angers S, Wilde A, Guttman DS, Desveaux D

    PLoS Pathog. 2012 Feb;8(2):e1002523

    PubMed PMID: 22319451

    Abstract

    The eukaryotic cytoskeleton is essential for structural support and intracellular transport, and is therefore a common target of animal pathogens. However, no phytopathogenic effector has yet been demonstrated to specifically target the plant cytoskeleton. Here we show that the Pseudomonas syringae type III secreted effector HopZ1a interacts with tubulin and polymerized microtubules. We demonstrate that HopZ1a is an acetyltransferase activated by the eukaryotic co-factor phytic acid. Activated HopZ1a acetylates itself and tubulin. The conserved autoacetylation site of the YopJ / HopZ superfamily, K289, plays a critical role in both the avirulence and virulence function of HopZ1a. Furthermore, HopZ1a requires its acetyltransferase activity to cause a dramatic decrease in Arabidopsis thaliana microtubule networks, disrupt the plant secretory pathway and suppress cell wall-mediated defense. Together, this study supports the hypothesis that HopZ1a promotes virulence through cytoskeletal and secretory disruption.

  • Quantitative interactor screening with next-generation sequencing (QIS-Seq) identified Arabidopsis thaliana MLO2 as a target of the Pseudomonas syringae type III effector HopZ2

    Quantitative interactor screening with next-generation sequencing (QIS-Seq) identified Arabidopsis thaliana MLO2 as a target of the Pseudomonas syringae type III effector HopZ2

    Lewis JD, Wan J, Ford R, Gong Y, Fung P, Nahal H, Wang PW, Desveaux D, Guttman DS

    BMC Genomics 2012 ;13():8

    PubMed PMID: 22230763

    Abstract

    Background. Here we describe the application of next-generation sequencing to yeast two-hybrid interaction screens and develop Quantitative Interactor Screen Identification of protein-protein interactions is a fundamental aspect of understanding protein function. A commonly used method for identifying protein interactions is the yeast two-hybrid system.

    Results. Here we describe the application of next-generation sequencing to yeast two-hybrid interaction screens and develop Quantitative Interactor Screen Sequencing (QIS-Seq). QIS-Seq provides a quantitative measurement of enrichment for each interactor relative to its frequency in the library as well as its general stickiness (non-specific binding). The QIS-Seq approach is scalable and can be used with any yeast two-hybrid screen and with any next-generation sequencing platform. The quantitative nature of QIS-Seq data make it amenable to statistical evaluation, and importantly, facilitates the standardization of experimental design, data collection, and data analysis. We applied QIS-Seq to identify the Arabidopsis thaliana MLO2 protein as a target of the Pseudomonas syringae type III secreted effector protein HopZ2. We validate the interaction between HopZ2 and MLO2 in planta and show that the interaction is required for HopZ2-associated virulence.

    Conclusions. We demonstrate that QIS-Seq is a high-throughput quantitative interactor screen and validate MLO2 as an interactor and novel virulence target of the P. syringae type III secreted effector HopZ2.