FPLC and liquid-chromatography mass spectrometry identify candidate necrosis-inducing proteins from culture filtrates of the fungal wheat pathogen Zymoseptoria tritici
M'Barek, S. Ben; Cordewener, J.H.G. ; Tabib Ghaffary, M.S. ; Lee, T.A.J. van der; Liu, Z. ; Mirzadi Gohari, A. ; Mehrabi, R. ; America, A.H.P. ; Friesen, T.L. ; Hamza, S. ; Stergiopoulos, I. ; Wit, P.J.G.M. de; Kema, G.H.J. - \ 2015
Fungal Genetics and Biology 79 (2015). - ISSN 1087-1845 - p. 54 - 62.
host-selective toxins - mycosphaerella-graminicola - stagonospora-nodorum - septoria-tritici - rhynchosporium-secalis - cladosporium-fulvum - ptr toxa - hydrogen-peroxide - barley pathogen - tan spot
Culture filtrates (CFs) of the fungal wheat pathogen Zymoseptoria tritici were assayed for necrosis-inducing activity after infiltration in leaves of various wheat cultivars. Active fractions were partially purified and characterized. The necrosis-inducing factors in CFs are proteinaceous, heat stable and their necrosis-inducing activity is temperature and light dependent. The in planta activity of CFs was tested by a time series of proteinase K (PK) co-infiltrations, which was unable to affect activity 30min after CF infiltrations. This suggests that the necrosis inducing proteins (NIPs) are either absent from the apoplast and likely actively transported into mesophyll cells or protected from the protease by association with a receptor. Alternatively, plant cell death signaling pathways might be fully engaged during the first 30min and cannot be reversed even after PK treatment. Further fractionation of the CFs with the highest necrosis-inducing activity involved fast performance liquid chromatography, SDS-PAGE and mass spectrometry. This revealed that most of the proteins present in the fractions have not been described before. The two most prominent ZtNIP encoding candidates were heterologously expressed in Pichia pastoris and subsequent infiltration assays showed their differential activity in a range of wheat cultivars.
Effector-triggered defence against apoplastic fungal pathogens
Stotz, H.U. ; Mitrousia, G.K. ; Wit, P.J.G.M. de; Fitt, B.D.L. - \ 2014
Trends in Plant Science 19 (2014)8. - ISSN 1360-1385 - p. 491 - 500.
programmed cell-death - plant immune-system - cf-2-dependent disease resistance - leptosphaeria-maculans - cladosporium-fulvum - brassica-napus - mycosphaerella-graminicola - avirulence gene - rhynchosporium-secalis - oilseed rape
R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed 'effector-triggered defence' (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops.
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.
Tomato Cf resistance proteins mediate recognition of cognate homologous effectors from fungi pathogenic on diots and monocots
Stergiopoulos, I. ; Burg, H.A. van den; Ökmen, B. ; Beenen, H.G. ; Liere, S. van; Kema, G.H.J. ; Wit, P.J.G.M. de - \ 2010
Proceedings of the National Academy of Sciences of the United States of America 107 (2010)16. - ISSN 0027-8424 - p. 7610 - 7615.
cladosporium-fulvum - virulence factor - rhynchosporium-secalis - disease resistance - selective toxin - gene - specificity - avr4 - arabidopsis - avirulence
Most fungal effectors characterized so far are species-specific and facilitate virulence on a particular host plant. During infection of its host tomato, Cladosporium fulvum secretes effectors that function as virulence factors in the absence of cognate Cf resistance proteins and induce effector-triggered immunity in their presence. Here we show that homologs of the C. fulvum Avr4 and Ecp2 effectors are present in other pathogenic fungi of the Dothideomycete class, including Mycosphaerella fijiensis, the causal agent of black Sigatoka disease of banana. We demonstrate that the Avr4 homolog of M. fijiensis is a functional ortholog of C. fulvum Avr4 that protects fungal cell walls against hydrolysis by plant chitinases through binding to chitin and, despite the low overall sequence homology, triggers a Cf-4-mediated hypersensitive response (HR) in tomato. Furthermore, three homologs of C. fulvum Ecp2 are found in M. fijiensis, one of which induces different levels of necrosis or HR in tomato lines that lack or contain a putative cognate Cf-Ecp2 protein, respectively. In contrast to Avr4, which acts as a defensive virulence factor, M. fijiensis Ecp2 likely promotes virulence by interacting with a putative host target causing host cell necrosis, whereas Cf-Ecp2 could possibly guard the virulence target of Ecp2 and trigger a Cf-Ecp2-mediated HR. Overall our data suggest that Avr4 and Ecp2 represent core effectors that are collectively recognized by single cognate Cf-proteins. Transfer of these Cf genes to plant species that are attacked by fungi containing these cognate core effectors provides unique ways for breeding disease-resistant crops
Fungal effector proteins
Stergiopoulos, I. ; Wit, P.J.G.M. de - \ 2009
Annual Review of Phytopathology 47 (2009). - ISSN 0066-4286 - p. 233 - 263.
pathogen cladosporium-fulvum - rice blast resistance - avirulence gene avr9 - flax rust resistance - cf-2-dependent disease resistance - powdery mildew resistance - race-specific elicitor - f-sp hordei - magnaporthe-grisea - rhynchosporium-secalis
It is accepted that most fungal avirulence genes encode virulence factors that are called effectors. Most fungal effectors are secreted, cysteine-rich proteins, and a role in virulence has been shown for a few of them, including Avr2 and Avr4 of Cladosporium fulvum, which inhibit plant cysteine proteases and protect chitin in fungal cell walls against plant chitinases, respectively. In resistant plants, effectors are directly or indirectly recognized by cognate resistance proteins that reside either inside the plant cell or on plasma membranes. Several secreted effectors function inside the host cell, but the uptake mechanism is not yet known. Variation observed among fungal effectors shows two types of selection that appear to relate to whether they interact directly or indirectly with their cognate resistance proteins. Direct interactions seem to favor point mutations in effector genes, leading to amino acid substitutions, whereas indirect interactions seem to favor jettison of effector genes.
Discovery of a functional Mycosphaerella teleomorph in the presumed asexual barley pathogen Septoria passerinii
Ware, S.B. ; Verstappen, E.C.P. ; Breeden, J. ; Cavaletto, J.R. ; Goodwin, S.B. ; Waalwijk, C. ; Crous, P.W. ; Kema, G.H.J. - \ 2007
Fungal Genetics and Biology 44 (2007)5. - ISSN 1087-1845 - p. 389 - 397.
mating-type idiomorphs - cryptococcus-neoformans - rhynchosporium-secalis - fusarium-oxysporum - leaf blotch - graminicola pathosystem - sexual reproduction - genetic-variation - tritici blotch - host cultivars
We studied the possibility of a teleomorph associated with the genotypically diverse septoria speckled leaf blotch (SSLB) pathogen of barley, Septoria passerinii. A teleomorph in the genus Mycosphaerella had been predicted previously based on phylogenetic analyses. This prediction was tested with experiments in the Netherlands and the United States by co-inoculating isolates with opposite mating types onto susceptible barley cultivars and monitoring leaves for sexual structures and for the discharge of ascospores. Characterization of putative hybrid progeny by both molecular (AFLP, RAPD, mating type, and ITS sequencing) and phenotypic analyses confirmed that a Mycosphaerella teleomorph of S. passerinii has been discovered approximately 125 years after the description of the anamorph. Progeny had recombinant genotypes of the molecular alleles present in the parents, and the identities of representative progeny isolates as S. passerinii were confirmed by ITS sequencing. A previously unknown sexual cycle explains the high degree of genetic variation among isolates found in nature. The experimental identification of a predicted teleomorph for S. passerinii indicates that cryptic sexual cycles may be common for many other ¿asexual¿ fungi with high levels of genotypic diversity.
Identification of QTLs for powdery mildew and scald resistance in barley
Shtaya, M.J.Y. ; Marcel, T.C. ; Sillero, J.C. ; Niks, R.E. ; Rubiales, D. - \ 2006
Euphytica 151 (2006)3. - ISSN 0014-2336 - p. 421 - 429.
quantitative trait loci - hordeum-vulgare l - erysiphe-graminis-hordei - rust puccinia-hordei - f-sp hordei - rhynchosporium-secalis - spring barley - ssp spontaneum - rflp markers - wild barley
A population of 103 recombinant inbred lines (RILs, F9-derived lines) developed from the two-row spring barley cross L94 × `Vada¿ was evaluated under field conditions for resistance against powdery mildew (Blumeria graminis f.sp. hordei) and scald (Rhynchosporium secalis). Apart from the major resistance gene mlo on chromosome 4 (4H), three QTLs (Rbgq1, Rbgq2 and Rbgq3) for resistance against powdery mildew were detected on chromosomes 2 (2H), 3 (3H), and 7 (5H), respectively. Rbgq1 and Rbgq2 have not been reported before, and did not map to a chromosome region where a major gene for powdery mildew had been reported. Four QTLs (Rrsq1, Rrsq2, Rrsq3 and Rrsq4) for resistance against scald were detected on chromosomes 3 (3H), 4 (4H) and 6 (6H). All four mapped to places where QTLs for scald resistance had been reported before in different populations