Genomics spurs rapid advances in our understanding of the biology of vascular wilt pathogens in the genus Verticillium
Klimes, A. ; Dobinson, K.F. ; Thomma, B. ; Klosterman, S.J. - \ 2015
Annual Review of Phytopathology 53 (2015). - ISSN 0066-4286 - p. 181 - 198.
protein-kinase gene - molecular characterization - functional-analysis - microsclerotia development - ethylene perception - hydrophobin gene - dahliae kleb - tomato ve1 - resistance - expression
The availability of genomic sequences of several Verticillium species triggered an explosion of genome-scale investigations of mechanisms fundamental to the Verticillium life cycle and disease process. Comparative genomics studies have revealed evolutionary mechanisms, such as hybridization and interchromosomal rearrangements, that have shaped these genomes. Functional analyses of a diverse group of genes encoding virulence factors indicate that successful host xylem colonization relies on specific Verticillium responses to various stresses, including nutrient deficiency and host defense–derived oxidative stress. Regulatory pathways that control responses to changes in nutrient availability also appear to positively control resting structure development. Conversely, resting structure development seems to be repressed by pathways, such as those involving effector secretion, which promote responses to host defenses. The genomics-enabled functional characterization of responses to the challenges presented by the xylem environment, accompanied by identification of novel virulence factors, has rapidly expanded our understanding of niche adaptation in Verticillium species.
The Brassicaceae-Specific EWR1 Gene Provides Resistance to Vascular Wilt Pathogens
Yadeta, K.A. ; Valkenburg, D.J. ; Hanemian, M. ; Marco, Y. ; Thomma, B.P.H.J. - \ 2014
PLoS ONE 9 (2014)2. - ISSN 1932-6203 - 11 p.
asymmetric interlaced pcr - arabidopsis-thaliana - verticillium wilt - antimicrobial peptides - defense peptides - tomato ve1 - plant - dahliae - disease - proteins
Soil-borne vascular wilt diseases caused by Verticillium spp. are among the most destructive diseases worldwide in a wide range of plant species. The most effective means of controlling Verticillium wilt diseases is the use of genetic resistance. We have previously reported the identification of four activation-tagged Arabidopsis mutants which showed enhanced resistance to Verticillium wilt. Among these, one mutant also showed enhanced resistance to Ralstonia solanacearum, a bacterial vascular wilt pathogen. Cloning of the activation tag revealed an insertion upstream of gene At3g13437, which we designated as EWR1 (for Enhancer of vascular Wilt Resistance 1) that encodes a putatively secreted protein of unknown function. The search for homologs of Arabidopsis EWR1 (AtEWR1) in public databases only identified homologs within the Brassicaceae family. We subsequently cloned the EWR1 homolog from Brassica oleracea (BoEWR1) and show that over-expression in Arabidopsis results in V. dahliae resistance. Moreover, over-expression of AtEWR1 and BoEWR1 in N. benthamiana, a member of the Solanaceae family, results in V. dahliae resistance, suggesting that EWR1 homologs can be used to engineer Verticillium wilt resistance in non-Brassicaceae crops as well.
Chaperones of the endoplasmic reticulum are required for Ve1-mediated resistance to Verticillium
Liebrand, T.W.H. ; Kombrink, A. ; Zhang, Z. ; Sklenar, J. ; Jones, A.M.E. ; Robatzek, S. ; Thomma, B.P.H.J. ; Joosten, M.H.A.J. - \ 2014
Molecular Plant Pathology 15 (2014)1. - ISSN 1464-6722 - p. 109 - 117.
receptor-like proteins - defective brassinosteroid receptor - pattern-recognition receptors - er quality-control - plant innate immunity - cell-surface - tomato ve1 - arabidopsis - gene - perception
The tomato receptor-like protein (RLP) Ve1 mediates resistance to the vascular fungal pathogen Verticillium dahliae. To identify the proteins required for Ve1 function, we transiently expressed and immunopurified functional Ve1-enhanced green fluorescent protein (eGFP) from Nicotiana benthamiana leaves, followed by mass spectrometry. This resulted in the identification of peptides originating from the endoplasmic reticulum (ER)-resident chaperones HSP70 binding proteins (BiPs) and a lectin-type calreticulin (CRT). Knock-down of the different BiPs and CRTs in tomato resulted in compromised Ve1-mediated resistance to V.dahliae in most cases, showing that these chaperones play an important role in Ve1 functionality. Recently, it has been shown that one particular CRT is required for the biogenesis of the RLP-type Cladosporium fulvum resistance protein Cf-4 of tomato, as silencing of CRT3a resulted in a reduced pool of complex glycosylated Cf-4 protein. In contrast, knock-down of the various CRTs in N.benthamiana or N.tabacum did not result in reduced accumulation of mature complex glycosylated Ve1 protein. Together, this study shows that the BiP and CRT ER chaperones differentially contribute to Cf-4- and Ve1-mediated immunity.
The Arabidopsis lectin receptor kinase LecRK-I.9 enhances resistance to Phytophthora infestans in Solanaceous plants
Bouwmeester, K. ; Han, M. ; Blanco-Portales, R. ; Song, W. ; Weide, R. ; Guo, L.Y. ; Vossen, E.A.G. van der; Govers, F. - \ 2014
Plant Biotechnology Journal 12 (2014)1. - ISSN 1467-7644 - p. 10 - 16.
interfamily transfer - potato cultivars - plasma-membrane - tomato ve1 - activation - expression - infection - proteins - lacking - gene
Phytophthora species are notorious plant pathogens which cause a variety of devastating crop diseases. Phytophthora pathogens secrete a plethora of effector proteins, several of which are known to interact with receptors in the host cell thereby either activating or suppressing defense responses. Unlike animals, plants lack an adaptive immune system; however, they are not defenseless and have acquired other mechanisms to withstand pathogens. Receptor proteins play important roles in sensing alterations at the plant cell wall and in mediating responses upon pathogen attack. This paper focuses on the Arabidopsis lectin receptor kinase LecRK-I.9, a mediator of cell wall – plasma membrane (CW-PM) adhesions that is known to bind in vitro to the Phytophthora infestans effector IPI-O via the cell attachment motif RGD. T-DNA mutants deficient in LecRK-I.9 and transgenic Arabidopsis lines expressing ipiO1 were found to behave as phenocopies. Both show a ‘gain-of-susceptibility’ phenotype towards the Arabidopsis pathogen Phytophthora brassicae and are disturbed in callose deposition. Overall, the results suggest that destabilizing the CW-PM continuum is a strategy for Phytophthora to promote infection. As countermeasure, the host may want to strengthen CW-PM adhesions, and the novel resistance component LecRK-I.9 apparently functions in this process
Ve1-mediated resistance against Verticillium does not involve a hypersensitive response in Arabidopsis
Zhang, Z. ; Esse, H.P. van; Damme, M. van; Fradin, E.F. ; Liu, Chun-Ming ; Thomma, B.P.H.J. - \ 2013
Molecular Plant Pathology 14 (2013)7. - ISSN 1464-6722 - p. 719 - 727.
ethylene-inducing xylanase - receptor-like proteins - gated ion-channel - disease resistance - rhynchosporium-secalis - functional-analysis - defense responses - gene family - tomato ve1 - cell-death
The recognition of pathogen effectors by plant immune receptors leads to the activation of immune responses that often include a hypersensitive response (HR): rapid and localized host cell death surrounding the site of attempted pathogen ingress. We have demonstrated previously that the recognition of the Verticillium dahliae effector protein Ave1 by the tomato immune receptor Ve1 triggers an HR in tomato and tobacco. Furthermore, we have demonstrated that tomato Ve1 provides Verticillium resistance in Arabidopsis upon Ave1 recognition. In this study, we investigated whether the co-expression of Ve1 and Ave1 in Arabidopsis results in an HR, which could facilitate a forward genetics screen. Surprisingly, we found that the co-expression of Ve1 and Ave1 does not induce an HR in Arabidopsis. These results suggest that an HR may occur as a consequence of Ve1/Ave1-induced immune signalling in tomato and tobacco, but is not absolutely required for Verticillium resistance.
Receptor-like kinase SOBIR1/EVR interacts with receptor-like proteins in plant immunity against fungal infection
Liebrand, T.W.H. ; Berg, G.C.M. van den; Zhang, Z. ; Smit, P. ; Cordewener, J.H.G. ; America, A.H.P. ; Sklenar, J. ; Jones, A.M.E. ; Tameling, W.I.L. ; Robatzek, S. ; Thomma, B.P.H.J. ; Joosten, M.H.A.J. - \ 2013
Proceedings of the National Academy of Sciences of the United States of America 110 (2013)24. - ISSN 0027-8424 - p. 10010 - 10015.
innate immunity - cladosporium-fulvum - verticillium resistance - citrx thioredoxin - plasma-membrane - tomato ve1 - cell-death - arabidopsis - perception - flagellin
The plant immune system is activated by microbial patterns that are detected as nonself molecules. Such patterns are recognized by immune receptors that are cytoplasmic or localized at the plasma membrane. Cell surface receptors are represented by receptor-like kinases (RLKs) that frequently contain extracellular leucine-rich repeats and an intracellular kinase domain for activation of downstream signaling, as well as receptor-like proteins (RLPs) that lack this signaling domain. It is therefore hypothesized that RLKs are required for RLPs to activate downstream signaling. The RLPs Cf-4 and Ve1 of tomato (Solanum lycopersicum) mediate resistance to the fungal pathogens Cladosporium fulvum and Verticillium dahliae, respectively. Despite their importance, the mechanism by which these immune receptors mediate downstream signaling upon recognition of their matching ligand, Avr4 and Ave1, remained enigmatic. Here we show that the tomato ortholog of the Arabidopsis thaliana RLK Suppressor Of BIR1-1/Evershed (SOBIR1/EVR) and its close homolog S. lycopersicum (Sl)SOBIR1-like interact in planta with both Cf-4 and Ve1 and are required for the Cf-4– and Ve1-mediated hypersensitive response and immunity. Tomato SOBIR1/EVR interacts with most of the tested RLPs, but not with the RLKs FLS2, SERK1, SERK3a, BAK1, and CLV1. SOBIR1/EVR is required for stability of the Cf-4 and Ve1 receptors, supporting our observation that these RLPs are present in a complex with SOBIR1/EVR in planta. We show that SOBIR1/EVR is essential for RLP-mediated immunity and propose that the protein functions as a regulatory RLK of this type of cell-surface receptors.
The Arabidopsis thaliana DNA-binding protein AHL19 mediates Verticillium wilt resistance
Yadeta, K.A. ; Hanemian, M. ; Smit, P. ; Hiemstra, J.A. ; Pereira, A. ; Marco, Y. ; Thomma, B.P.H.J. - \ 2011
Molecular Plant-Microbe Interactions 24 (2011)12. - ISSN 0894-0282 - p. 1582 - 1591.
at-hook protein - ralstonia-solanacearum - microbial pathogens - gene-expression - albo-atrum - tomato ve1 - disease - dahliae - defense - identification
Verticillium spp. are destructive soilborne fungal pathogens that cause vascular wilt diseases in a wide range of plant species. Verticillium wilts are particularly notorious, and genetic resistance in crop plants is the most favorable means of disease control. In a gain-of-function screen using an activation-tagged Arabidopsis mutant collection, we identified four mutants, A1 to A4, which displayed enhanced resistance toward the vascular wilt species Verticillium dahliae, V. albo-atrum and V. longisporum but not to Fusarium oxysporum f. sp. raphani. Further testing revealed that mutant A2 displayed enhanced Ralstonia solanacearum resistance, while mutants A1 and A3 were more susceptible toward Pseudomonas syringae pv. tomato. Identification of the activation tag insertion site in the A1 mutant revealed an insertion in close proximity to the gene encoding AHL19, which was constitutively expressed in the mutant. AHL19 knock-out alleles were found to display enhanced Verticillium susceptibility whereas overexpression of AHL19 resulted in enhanced Verticillium resistance, showing that AHL19 acts as a positive regulator of plant defense.