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Comparative Genomic Analyses of Multiple Pseudomonas Strains Infecting Corylus avellana Trees Reveal the Occurrence of Two Genetic Clusters with Both Common and Distinctive Virulence and Fitness Traits.

Marcelletti S, Scortichini M - PLoS ONE (2015)

Bottom Line: Between these two clusters, no recombination event was found.Homologue genes of the antimetabolite mangotoxin and ice nucleation activity clusters were found solely in all P. syringae pathovar strains, whereas the siderophore yersiniabactin was only present in P. avellanae.By contrast, they do not have genes coding for indolacetic acid and anti-insect toxin.

View Article: PubMed Central - PubMed

Affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (C.R.A.)-Centro di Ricerca per la Frutticoltura, Via di Fioranello 52, I-00134, Roma, Italy.

ABSTRACT
The European hazelnut (Corylus avellana) is threatened in Europe by several pseudomonads which cause symptoms ranging from twig dieback to tree death. A comparison of the draft genomes of nine Pseudomonas strains isolated from symptomatic C. avellana trees was performed to identify common and distinctive genomic traits. The thorough assessment of genetic relationships among the strains revealed two clearly distinct clusters: P. avellanae and P. syringae. The latter including the pathovars avellanae, coryli and syringae. Between these two clusters, no recombination event was found. A genomic island of approximately 20 kb, containing the hrp/hrc type III secretion system gene cluster, was found to be present without any genomic difference in all nine pseudomonads. The type III secretion system effector repertoires were remarkably different in the two groups, with P. avellanae showing a higher number of effectors. Homologue genes of the antimetabolite mangotoxin and ice nucleation activity clusters were found solely in all P. syringae pathovar strains, whereas the siderophore yersiniabactin was only present in P. avellanae. All nine strains have genes coding for pectic enzymes and sucrose metabolism. By contrast, they do not have genes coding for indolacetic acid and anti-insect toxin. Collectively, this study reveals that genomically different Pseudomonas can converge on the same host plant by suppressing the host defence mechanisms with the use of different virulence weapons. The integration into their genomes of a horizontally acquired genomic island could play a fundamental role in their evolution, perhaps giving them the ability to exploit new ecological niches.

No MeSH data available.


Related in: MedlinePlus

Divergence dendrogram based on the concatenated dataset of the four housekeeping genes.The dendrogram was built assessing gapA, gltA, gyrB, rpoD genes and by applying the E. coli-Salmonella model to nine pseudomonad strains infecting Corylus avellana. MYA: millions of years before present. Strain legend is shown in Table 1. Pseudomonas cannabina pv. alisalensis Pcal BS91 was included in the analysis as outgroup.
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pone.0131112.g004: Divergence dendrogram based on the concatenated dataset of the four housekeeping genes.The dendrogram was built assessing gapA, gltA, gyrB, rpoD genes and by applying the E. coli-Salmonella model to nine pseudomonad strains infecting Corylus avellana. MYA: millions of years before present. Strain legend is shown in Table 1. Pseudomonas cannabina pv. alisalensis Pcal BS91 was included in the analysis as outgroup.

Mentions: The putative divergence time between the two genomospecies for the four housekeeping genes was calculated according to two different estimations. By following the Escherichia coli-Salmonella typhimurium model based on a substitution rate of 1 x 109 substitutions per year, the most common recent ancestor for the two species was estimated to have occurred between 41.8 and 142.0 million years ago. However, according to the Staphylococcus aureus model based on a substitution rate of 1 x 106 substitutions per year, the most common recent ancestor for these two species instead occurred between 28.700 to 94.900 years before present (Table 4). The corresponding dendrogram based on the concatenated dataset of the four housekeeping genes obtained using the DensiTree software and built based on the E. coli-S. typhimurium model (Fig 4) suggests that the two clusters diverged approximately 82 millions of years before present.


Comparative Genomic Analyses of Multiple Pseudomonas Strains Infecting Corylus avellana Trees Reveal the Occurrence of Two Genetic Clusters with Both Common and Distinctive Virulence and Fitness Traits.

Marcelletti S, Scortichini M - PLoS ONE (2015)

Divergence dendrogram based on the concatenated dataset of the four housekeeping genes.The dendrogram was built assessing gapA, gltA, gyrB, rpoD genes and by applying the E. coli-Salmonella model to nine pseudomonad strains infecting Corylus avellana. MYA: millions of years before present. Strain legend is shown in Table 1. Pseudomonas cannabina pv. alisalensis Pcal BS91 was included in the analysis as outgroup.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492584&req=5

pone.0131112.g004: Divergence dendrogram based on the concatenated dataset of the four housekeeping genes.The dendrogram was built assessing gapA, gltA, gyrB, rpoD genes and by applying the E. coli-Salmonella model to nine pseudomonad strains infecting Corylus avellana. MYA: millions of years before present. Strain legend is shown in Table 1. Pseudomonas cannabina pv. alisalensis Pcal BS91 was included in the analysis as outgroup.
Mentions: The putative divergence time between the two genomospecies for the four housekeeping genes was calculated according to two different estimations. By following the Escherichia coli-Salmonella typhimurium model based on a substitution rate of 1 x 109 substitutions per year, the most common recent ancestor for the two species was estimated to have occurred between 41.8 and 142.0 million years ago. However, according to the Staphylococcus aureus model based on a substitution rate of 1 x 106 substitutions per year, the most common recent ancestor for these two species instead occurred between 28.700 to 94.900 years before present (Table 4). The corresponding dendrogram based on the concatenated dataset of the four housekeeping genes obtained using the DensiTree software and built based on the E. coli-S. typhimurium model (Fig 4) suggests that the two clusters diverged approximately 82 millions of years before present.

Bottom Line: Between these two clusters, no recombination event was found.Homologue genes of the antimetabolite mangotoxin and ice nucleation activity clusters were found solely in all P. syringae pathovar strains, whereas the siderophore yersiniabactin was only present in P. avellanae.By contrast, they do not have genes coding for indolacetic acid and anti-insect toxin.

View Article: PubMed Central - PubMed

Affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (C.R.A.)-Centro di Ricerca per la Frutticoltura, Via di Fioranello 52, I-00134, Roma, Italy.

ABSTRACT
The European hazelnut (Corylus avellana) is threatened in Europe by several pseudomonads which cause symptoms ranging from twig dieback to tree death. A comparison of the draft genomes of nine Pseudomonas strains isolated from symptomatic C. avellana trees was performed to identify common and distinctive genomic traits. The thorough assessment of genetic relationships among the strains revealed two clearly distinct clusters: P. avellanae and P. syringae. The latter including the pathovars avellanae, coryli and syringae. Between these two clusters, no recombination event was found. A genomic island of approximately 20 kb, containing the hrp/hrc type III secretion system gene cluster, was found to be present without any genomic difference in all nine pseudomonads. The type III secretion system effector repertoires were remarkably different in the two groups, with P. avellanae showing a higher number of effectors. Homologue genes of the antimetabolite mangotoxin and ice nucleation activity clusters were found solely in all P. syringae pathovar strains, whereas the siderophore yersiniabactin was only present in P. avellanae. All nine strains have genes coding for pectic enzymes and sucrose metabolism. By contrast, they do not have genes coding for indolacetic acid and anti-insect toxin. Collectively, this study reveals that genomically different Pseudomonas can converge on the same host plant by suppressing the host defence mechanisms with the use of different virulence weapons. The integration into their genomes of a horizontally acquired genomic island could play a fundamental role in their evolution, perhaps giving them the ability to exploit new ecological niches.

No MeSH data available.


Related in: MedlinePlus