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Type Three Secretion System in Pseudomonas savastanoi Pathovars: Does Timing Matter?

Tegli S, Gori A, Cerboneschi M, Cipriani MG, Sisto A - Genes (Basel) (2011)

Bottom Line: Pseudomonas savastanoi pv. savastanoi is the causal agent of Olive knot disease, relying on the Type Three Secretion System (TTSS) for its pathogenicity.In this regard, nothing was known about the two other pathovars belonging to this species, pv. nerii and pv. fraxini, characterized by a different host range.Moreover, by Real-Time PCR we analyzed the in vitro expression of four main TTSS genes, revealing different activation patterns in the three pathovars, hypothetically related to their diverse virulence behaviors.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio di Patologia Vegetale Molecolare, Dipartimento di Biotecnologie Agrarie, Universit√° degli Studi di Firenze, Via della Lastruccia 10, 50019 Sesto Fiorentino, Firenze, Italy. stefania.tegli@unifi.it.

ABSTRACT
Pseudomonas savastanoi pv. savastanoi is the causal agent of Olive knot disease, relying on the Type Three Secretion System (TTSS) for its pathogenicity. In this regard, nothing was known about the two other pathovars belonging to this species, pv. nerii and pv. fraxini, characterized by a different host range. Here we report on the organization of the entire TTSS cluster on the three pathovars, and a phylogenetic analysis including the TTSS of those bacteria belonging to the P. syringae complex sequenced so far, highlighting the evolution of each operon (hrpC, hrpJ, hrpRS, hrpU and hrpZ). Moreover, by Real-Time PCR we analyzed the in vitro expression of four main TTSS genes, revealing different activation patterns in the three pathovars, hypothetically related to their diverse virulence behaviors.

No MeSH data available.


Related in: MedlinePlus

Time course of hrpL, hrpA, hrpS and hrpV expression in P. savastanoi pv. fraxinii (Psf134), pv. savastanoi (Psv5) and pv. nerii (Psn23). Relative expression in minimal medium (MM) is reported, setting expression in King's B medium (KB) as reference [59]. The pathovar referred to each graph is reported as graph title. The color used for each gene is indicated in the label. The vertical lines indicate standard deviation values, and where they are absent, the limits were within the symbol dimensions. The numerical values for each point analyzed are reported in Table S3.
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f3-genes-02-00957: Time course of hrpL, hrpA, hrpS and hrpV expression in P. savastanoi pv. fraxinii (Psf134), pv. savastanoi (Psv5) and pv. nerii (Psn23). Relative expression in minimal medium (MM) is reported, setting expression in King's B medium (KB) as reference [59]. The pathovar referred to each graph is reported as graph title. The color used for each gene is indicated in the label. The vertical lines indicate standard deviation values, and where they are absent, the limits were within the symbol dimensions. The numerical values for each point analyzed are reported in Table S3.

Mentions: The results obtained are reported in Figure 3 and in Table S3. For the first time it was demonstrated that TTSS genes are overexpressed in cultural conditions mimicking the plant apoplast in each of the three P. savastanoi pathovars here examined. Moreover pathovar-specific expression patterns were observed. In particular, the highest values for the relative expression of both hrpA and hrpS were reached by Psf134 after three hours, while hrpL peaked at six hours (Figure 3). The expression of all genes dropped off after 18 h with the exception of hrpV, supposed to be an inhibitor of HrpS action [12,17], that increased up to a level of 80 fold after one day from the beginning of the simulated infection. Different expression patterns were shown by Psv5 (Figure 3). Relative expression levels of hrpA, hrpL and hrpS remained low for the first 18 h of growth on MM, after which they started to rise and reached levels ranging from 124.7 to 152.1 fold at 24 h. As expected, hrpV followed an opposite trend, since its highest relative expression level was reached after 6 h of bacterial growth on MM (53.2 fold). As far as Psn23 is concerned, the expression pattern of TTSS genes seemed to be more finely tuned (Figure 3). In particular, the highest relative expression levels for hrpA and hrpS were reached after 18 h, and then they started to decrease. The genes hrpV and hrpL peaked at 3 h of growth on MM. While hrpV signals progressively decreased until the end of the experiment, hrpL had a slight but continuous recovery up to 24 h (22.4 fold).


Type Three Secretion System in Pseudomonas savastanoi Pathovars: Does Timing Matter?

Tegli S, Gori A, Cerboneschi M, Cipriani MG, Sisto A - Genes (Basel) (2011)

Time course of hrpL, hrpA, hrpS and hrpV expression in P. savastanoi pv. fraxinii (Psf134), pv. savastanoi (Psv5) and pv. nerii (Psn23). Relative expression in minimal medium (MM) is reported, setting expression in King's B medium (KB) as reference [59]. The pathovar referred to each graph is reported as graph title. The color used for each gene is indicated in the label. The vertical lines indicate standard deviation values, and where they are absent, the limits were within the symbol dimensions. The numerical values for each point analyzed are reported in Table S3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927595&req=5

f3-genes-02-00957: Time course of hrpL, hrpA, hrpS and hrpV expression in P. savastanoi pv. fraxinii (Psf134), pv. savastanoi (Psv5) and pv. nerii (Psn23). Relative expression in minimal medium (MM) is reported, setting expression in King's B medium (KB) as reference [59]. The pathovar referred to each graph is reported as graph title. The color used for each gene is indicated in the label. The vertical lines indicate standard deviation values, and where they are absent, the limits were within the symbol dimensions. The numerical values for each point analyzed are reported in Table S3.
Mentions: The results obtained are reported in Figure 3 and in Table S3. For the first time it was demonstrated that TTSS genes are overexpressed in cultural conditions mimicking the plant apoplast in each of the three P. savastanoi pathovars here examined. Moreover pathovar-specific expression patterns were observed. In particular, the highest values for the relative expression of both hrpA and hrpS were reached by Psf134 after three hours, while hrpL peaked at six hours (Figure 3). The expression of all genes dropped off after 18 h with the exception of hrpV, supposed to be an inhibitor of HrpS action [12,17], that increased up to a level of 80 fold after one day from the beginning of the simulated infection. Different expression patterns were shown by Psv5 (Figure 3). Relative expression levels of hrpA, hrpL and hrpS remained low for the first 18 h of growth on MM, after which they started to rise and reached levels ranging from 124.7 to 152.1 fold at 24 h. As expected, hrpV followed an opposite trend, since its highest relative expression level was reached after 6 h of bacterial growth on MM (53.2 fold). As far as Psn23 is concerned, the expression pattern of TTSS genes seemed to be more finely tuned (Figure 3). In particular, the highest relative expression levels for hrpA and hrpS were reached after 18 h, and then they started to decrease. The genes hrpV and hrpL peaked at 3 h of growth on MM. While hrpV signals progressively decreased until the end of the experiment, hrpL had a slight but continuous recovery up to 24 h (22.4 fold).

Bottom Line: Pseudomonas savastanoi pv. savastanoi is the causal agent of Olive knot disease, relying on the Type Three Secretion System (TTSS) for its pathogenicity.In this regard, nothing was known about the two other pathovars belonging to this species, pv. nerii and pv. fraxini, characterized by a different host range.Moreover, by Real-Time PCR we analyzed the in vitro expression of four main TTSS genes, revealing different activation patterns in the three pathovars, hypothetically related to their diverse virulence behaviors.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio di Patologia Vegetale Molecolare, Dipartimento di Biotecnologie Agrarie, Universit√° degli Studi di Firenze, Via della Lastruccia 10, 50019 Sesto Fiorentino, Firenze, Italy. stefania.tegli@unifi.it.

ABSTRACT
Pseudomonas savastanoi pv. savastanoi is the causal agent of Olive knot disease, relying on the Type Three Secretion System (TTSS) for its pathogenicity. In this regard, nothing was known about the two other pathovars belonging to this species, pv. nerii and pv. fraxini, characterized by a different host range. Here we report on the organization of the entire TTSS cluster on the three pathovars, and a phylogenetic analysis including the TTSS of those bacteria belonging to the P. syringae complex sequenced so far, highlighting the evolution of each operon (hrpC, hrpJ, hrpRS, hrpU and hrpZ). Moreover, by Real-Time PCR we analyzed the in vitro expression of four main TTSS genes, revealing different activation patterns in the three pathovars, hypothetically related to their diverse virulence behaviors.

No MeSH data available.


Related in: MedlinePlus