Dataset Information

Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica.

ABSTRACT: Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish pathogen, Saprolegnia parasitica. Approximately 1/3 of the assembled genome exhibits loss of heterozygosity, indicating an efficient mechanism for revealing new variation. Comparison of S. parasitica with plant pathogenic oomycetes suggests that during evolution the host cellular environment has driven distinct patterns of gene expansion and loss in the genomes of plant and animal pathogens. S. parasitica possesses one of the largest repertoires of proteases (270) among eukaryotes that are deployed in waves at different points during infection as determined from RNA-Seq data. In contrast, despite being capable of living saprotrophically, parasitism has led to loss of inorganic nitrogen and sulfur assimilation pathways, strikingly similar to losses in obligate plant pathogenic oomycetes and fungi. The large gene families that are hallmarks of plant pathogenic oomycetes such as Phytophthora appear to be lacking in S. parasitica, including those encoding RXLR effectors, Crinkler's, and Necrosis Inducing-Like Proteins (NLP). S. parasitica also has a very large kinome of 543 kinases, 10% of which is induced upon infection. Moreover, S. parasitica encodes several genes typical of animals or animal-pathogens and lacking from other oomycetes, including disintegrins and galactose-binding lectins, whose expression and evolutionary origins implicate horizontal gene transfer in the evolution of animal pathogenesis in S. parasitica.

SUBMITTER: Jiang RH

PROVIDER: S-EPMC3681718 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica.

Jiang Rays H Y RH de Bruijn Irene I Haas Brian J BJ Belmonte Rodrigo R Löbach Lars L Christie James J van den Ackerveken Guido G Bottin Arnaud A Bulone Vincent V Díaz-Moreno Sara M SM Dumas Bernard B Fan Lin L Gaulin Elodie E Govers Francine F Grenville-Briggs Laura J LJ Horner Neil R NR Levin Joshua Z JZ Mammella Marco M Meijer Harold J G HJ Morris Paul P Nusbaum Chad C Oome Stan S Phillips Andrew J AJ van Rooyen David D Rzeszutek Elzbieta E Saraiva Marcia M Secombes Chris J CJ Seidl Michael F MF Snel Berend B Stassen Joost H M JH Sykes Sean S Tripathy Sucheta S van den Berg Herbert H Vega-Arreguin Julio C JC Wawra Stephan S Young Sarah K SK Zeng Qiandong Q Dieguez-Uribeondo Javier J Russ Carsten C Tyler Brett M BM van West Pieter P

PLoS genetics 20130613 6

Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish pathogen, Saprolegnia parasitica. Approximately 1/3 of the assembled genome exhibits loss of heterozygosity, indicating an efficient mechanism for revealing new variation. Comparison of S. parasitica with ...[more]

PMID: 23785293

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Project description:The secondary cysts of the fish pathogen oomycete Saprolegnia parasitica possess bundles of long hooked hairs that are characteristic to this economically important pathogenic species. Few studies have been carried out on elucidating their specific role in the S. parasitica life cycle and the role they may have in the infection process. We show here their function by employing several strategies that focus on descriptive, developmental and predictive approaches. The strength of attachment of the secondary cysts of this pathogen was compared to other closely related species where bundles of long hooked hairs are absent. We found that the attachment of the S. parasitica cysts was around three times stronger than that of other species. The time sequence and influence of selected factors on morphology and the number of the bundles of long hooked hairs conducted by scanning electron microscopy study revealed that these are dynamic structures. They are deployed early after encystment, i.e., within 30 sec of zoospore encystment, and the length, but not the number, of the bundles steadily increased over the encystment period. We also observed that the number and length of the bundles was influenced by the type of substrate and encystment treatment applied, suggesting that these structures can adapt to different substrates (glass or fish scales) and can be modulated by different signals (i.e., protein media, 50 mM CaCl2 concentrations, carbon particles). Immunolocalization studies evidenced the presence of an adhesive extracellular matrix. The bioinformatic analyses of the S. parasitica secreted proteins showed that there is a high expression of genes encoding domains of putative proteins related to the attachment process and cell adhesion (fibronectin and thrombospondin) coinciding with the deployment stage of the bundles of long hooked hairs formation. This suggests that the bundles are structures that might contribute to the adhesion of the cysts to the host because they are composed of these adhesive proteins and/or by increasing the surface of attachment of this extracellular matrix.

Dataset Information

Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica.

Publications

Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica.

Similar Datasets

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