Presence/absence polymorphism for alternative pathogenicity islands in Pseudomonas viridiflava , a pathogen of Arabidopsis
| Autor: | Erica M. Goss, Martin Kreitman, Dacheng Tian, Hitoshi Araki, Katrin Jakob, Solveig S Halldorsdottir, Joy Bergelson |
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| Rok vydání: | 2006 |
| Předmět: |
Genetics
Polymorphism Genetic Multidisciplinary Pseudomonas viridiflava Molecular Sequence Data Arabidopsis Virulence Biological Sciences Biology Balancing selection biology.organism_classification Pathogenicity island Evolution Molecular Pseudomonas Horizontal gene transfer Genotype Gene Pathogen Genome Plant Phylogeny Plant Diseases |
| Zdroj: | Proceedings of the National Academy of Sciences. 103:5887-5892 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | The contribution of arms race dynamics to plant–pathogen coevolution has been called into question by the presence of balanced polymorphisms in resistance genes of Arabidopsis thaliana , but less is known about the pathogen side of the interaction. Here we investigate structural polymorphism in pathogenicity islands (PAIs) in Pseudomonas viridiflava , a prevalent bacterial pathogen of A. thaliana . PAIs encode the type III secretion system along with its effectors and are essential for pathogen recognition in plants. P. viridiflava harbors two structurally distinct and highly diverged PAI paralogs (T- and S-PAI) that are integrated in different chromosome locations in the P. viridiflava genome. Both PAIs are segregating as presence/absence polymorphisms such that only one PAI ([T-PAI, ∇S-PAI] and [∇T-PAI, S-PAI]) is present in any individual cell. A worldwide population survey identified no isolate with neither or both PAI. T-PAI and S-PAI genotypes exhibit virulence differences and a host-specificity tradeoff. Orthologs of each PAI can be found in conserved syntenic locations in other Pseudomonas species, indicating vertical phylogenetic transmission in this genus. Molecular evolutionary analysis of PAI sequences also argues against “recent” horizontal transfer. Spikes in nucleotide divergence in flanking regions of PAI and ∇-PAI alleles suggest that the dual PAI polymorphism has been maintained in this species under some form of balancing selection. Virulence differences and host specificities are hypothesized to be responsible for the maintenance of the dual PAI system in this bacterial pathogen. |
| Databáze: | OpenAIRE |
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