Identification of host-specific effectors mediating pathogenicity of the vascular wilt pathogen Verticillium dahliae

Verticillium dahliae is an economically important pathogen causing vascular wilt on over 160 plant species. In North America, potato early dying is a significant disease of potato, especially in the midwest and Pacific northwest states. This disease is caused by the fungus Verticillium dahliae and in some cases involves a synergistic interaction with root-lesion nematodes, primarily Pratylenchus penetrans. In Israel, Verticillium wilt occurs in many regions and inflicts serious losses in potato, cotton, and other crops. Objectives of this project were to establish a large collection of isolates of Verticillium dahliae from potato (USA) and several host plants (Israel) and to characterize and compare the isolates with regard to morphology, vegetative compatibility group (VCG), and pathogenic capabilities on several hosts. Isolations were made from 224 commercial lots of certified potato seed tubers from across N. America and 87 potato fields located in the Columbia Basin of Oregon and Washington. A large collection of isolates from central U.S. states already existed. In Israel, 47 field sites were sampled and isolates of Verticillium dahliae were recovered from 13 host plant species and from soil. Potato isolates from N. America were tested for vegetative compatibility and all found to be in VCG 4 with about 2/3 in VCG 4A and the rest in VCG 4B. VCG 4A isolates were significantly more aggressive on potato than VCG 4B isolates and were more likely to interact synergistically with P. penetrans. The Israeli isolates fell into three vegetative compatibility groups. Nearly all (> 90%) VCG2B and VCG 4B isolates were recovered from the northern and southern parts of Israel, respectively, with some overlap in central areas. Several pathotypes were defined in cotton, using cotton and eggplant together as differentials. All VCG 2B isolates from cotton caused severe disease in cotton, while VCG 2A and VCG 4B isolates from several crops were much less aggressive to cotton. When Israeli isolates of VCGs 2A, 2B and 4B were inoculated to potato and tomato, VCG 4B isolates caused much more severe disease on potato and VCG 2A isolates caused much more severe disease in tomato. Differential patterns of pathogenicity and aggressiveness of these VCGs on potato and tomato were consistent regardless of the host plant of origin. Isolates of the same VCG resembled one another more than isolates from different VCGs based on colony and microsclerotial morphology, temperature responses and, partially, in pathogenicity. Vegetative compatibility grouping of V. dahliae in Israel appears closely associated with specific pathogenicity and other phenotypic traits. The absence of VCG 4A in Israel is significant. VCG patterns among Verficillium populations are useful to predict relatedness and pathogenic potential in both countries.

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Comparative genomics of Verticillium dahliae isolates reveals the in planta-secreted effector protein recognized in V2 tomato plants

10.1101/2020.06.16.154641 ◽

2020 ◽

Cited By ~ 1

Author(s):

Edgar A. Chavarro-Carrero ◽

Jasper P. Vermeulen ◽

David E. Torres ◽

Toshiyuki Usami ◽

Henk J. Schouten ◽

...

Keyword(s):

Comparative Genomics ◽

Verticillium Dahliae ◽

Plant Pathogens ◽

Effector Protein ◽

Vascular Wilt ◽

In Planta ◽

Specific Sequence ◽

Tomato Plants ◽

Tomato Cultivars ◽

Race 2

SUMMARYPlant pathogens secrete effector molecules during host invasion to promote host colonization. However, some of these effectors become recognized by host receptors, encoded by resistance genes, to mount defense response and establish immunity. Recently, a novel resistance was identified in tomato, mediated by the single dominant V2 locus, to control strains of the soil-borne vascular wilt fungus Verticillium dahliae that belong to race 2. We performed comparative genomics between race 2 strains and resistance-breaking race 3 strains to identify the avirulence effector that activates V2 resistance, termed Av2. We identified 277 kb of race 2-specific sequence comprising only two genes that encode predicted secreted proteins, both of which are expressed by V. dahliae during tomato colonization. Subsequent functional analysis based on genetic complementation into race 3 isolates confirmed that one of the two candidates encodes the avirulence effector Av2 that is recognized in V2 tomato plants. The identification of Av2 will not only be helpful to select tomato cultivars that are resistant to race 2 strains of V. dahliae, as the corresponding V2 resistance gene has not yet been mapped, but also to monitor adaptations in the V. dahliae population to deployment of V2-containing tomato cultivars in agriculture.

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Reaction of Some Olive Cultivars to Verticillium dahliae Isolates Agent of Vascular Wilt: A Comparative Study

American Journal of Experimental Agriculture ◽

10.9734/ajea/2011/521 ◽

2011 ◽

Vol 1 (4) ◽

pp. 320-330

Author(s):

S. Sanei

Keyword(s):

Comparative Study ◽

Verticillium Dahliae ◽

Vascular Wilt ◽

Olive Cultivars

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Scarcity of Major Resistance Genes Against Verticillium Dahliae

10.21203/rs.3.rs-951751/v1 ◽

2021 ◽

Author(s):

Jasper P. Vermeulen ◽

Katharina Hanika ◽

Bart P.H.J. Thomma ◽

Yuling Bai ◽

Henk J Schouten

Keyword(s):

Resistance Genes ◽

Verticillium Dahliae ◽

Fungal Pathogen ◽

Wilt Disease ◽

Discriminative Power ◽

Vascular Wilt ◽

Virulent Strains ◽

Canopy Area ◽

Major Resistance Genes ◽

Vascular Wilt Disease

Abstract Verticillium dahliae is a soil-borne fungal pathogen that causes vascular wilt disease in numerous plant species. The only described qualitative resistances against V. dahliae are the Ve1 gene and the V2 locus in tomato. These resistances have been overcome by virulent strains. We tried to identify additional resistances. Out of the methods we tested, comparing the canopy area of V. dahliae-inoculated plants with mock-inoculated plants yielded the best discriminative power in resistance tests. Out of six wild tomato accessions that were previously reported to possess some resistance, Solanum pimpinellifolium G1.1596 and S. cheesmanii G1.1615 displayed the lowest stunting and the least colonization by V. dahliae. Recombinant inbred line (RIL) populations were developed of both populations. No QTLs were identified in the G1.1596 RIL population. In the G1.1615 population, four small-effect QTLs were associated with reduced stunting. Many studies in other hosts also failed to discover major resistance genes against V. dahliae. We hypothesize that the scarcity of major resistance genes against V. dahliae is caused by its endophytic behaviour in nature. The limited damage in nature would not lead to evolutionary pressure to evolve major resistances. However, in agriculture V. dahliae can behave more pathogenic, leading to serious damage.

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Genomewide Transcriptome Profiles Reveal How Bacillus subtilis Lipopeptides Inhibit Microsclerotia Formation in Verticillium dahliae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-08-18-0233-r ◽

2019 ◽

Vol 32 (5) ◽

pp. 622-634 ◽

Cited By ~ 6

Author(s):

Dimei Yu ◽

Yulin Fang ◽

Chen Tang ◽

Steven J. Klosterman ◽

Chengming Tian ◽

...

Keyword(s):

Mass Spectrometry ◽

Bacillus Subtilis ◽

Verticillium Dahliae ◽

Vascular Wilt ◽

Protein Catabolism ◽

Antifungal Substance ◽

High Osmolarity ◽

High Osmolarity Glycerol ◽

Expression Of Genes ◽

Response To Stress

Verticillium dahliae is a soilborne fungus and the primary causal agent of vascular wilt diseases worldwide. The fungus produces melanized microsclerotia that are crucially important for the survival and spread of V. dahliae. There are no fungicides available that are both effective and environmentally friendly to suppress the fungus. Previously, Bacillus subtilis C232 was isolated from soil and was demonstrated to suppress microsclerotia formation in V. dahliae. In this study, liquid chromatography coupled with mass spectrometry revealed that the antifungal substance is actually a mixture of lipopeptides. Exposure of V. dahliae to these lipopeptides resulted in hyphal swelling, cell lysis, and downregulation of melanin-related genes. RNA sequencing analyses of the lipopeptide-suppressed transcriptome during microsclerotial development revealed that 5,974 genes (2,131 upregulated and 3,843 downregulated) were differentially expressed versus nonsuppressive conditions. Furthermore, gene ontology enrichment analyses revealed that genes involved in response to stress, cellular metabolic processes, and translation were significantly enriched. Additionally, the lipopeptides inhibited expression of genes associated with secondary metabolism, protein catabolism, and the high-osmolarity glycerol response signaling pathway. Together, these findings provide evidence for the mechanism by which B. subtilis lipopeptides suppress microsclerotia formation. The transcriptomic insight garnered here may facilitate the development of biological agents to combat Verticillium wilt.

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Characterization of the glyoxalase I gene from the vascular wilt fungus Verticillium dahliae

Canadian Journal of Microbiology ◽

10.1139/w06-033 ◽

2006 ◽

Vol 52 (9) ◽

pp. 816-822 ◽

Cited By ~ 6

Author(s):

A Klimes ◽

M J Neumann ◽

S J Grant ◽

K F Dobinson

Keyword(s):

Verticillium Dahliae ◽

Glyoxalase I ◽

Vascular Wilt ◽

Glyoxalase System ◽

Enhanced Sensitivity ◽

Acid Protein ◽

Gene Homologue ◽

I Gene ◽

Amino Acid Protein

A glyoxalase I gene homologue (VdGLO1) was identified in the vascular wilt fungus Verticillium dahliae by sequence tag analysis of genes expressed during resting structure development. The results of the current study show that the gene encodes a putative 345 amino acid protein with high similarity to glyoxalase I, which produces S-D-lactoylglutathione from the toxic metabolic by-product methylglyoxal (MG). Disruption of the V. dahliae gene by Agrobacterium tumefaciens-mediated transformation resulted in enhanced sensitivity to MG. Mycelial growth of disruption mutants was severely reduced in the presence of 5 mmol/L MG. In contrast, spore production in liquid medium was abolished at 1 mmol/L MG, although not at physiologically relevant concentrations of ≤100 µmol/L. In this first report on the characterization of a glyoxalase I gene in a vascular wilt pathogen, we found that disruption of VdGLO1 had no discernable effect on the pathogenicity of V. dahliae. These data suggest that while the glyoxalase system is necessary for effectively dealing with catastrophic levels of MG, under normal conditions of growth and infection, other MG detoxification pathways in V. dahliae are able to compensate for the absence of the glyoxalase system.Key words: verticillium wilt, glycolytic methylglyoxal pathway, 2-oxoaldehydes.

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