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Global Analysis of Type Three Secretion System and Quorum Sensing Inhibition of Pseudomonas savastanoi by Polyphenols Extracts from Vegetable Residues

View Article: PubMed Central - PubMed

ABSTRACT

Protection of plants against bacterial diseases still mainly relies on the use of chemical pesticides, which in Europe correspond essentially to copper-based compounds. However, recently plant diseases control is oriented towards a rational use of molecules and extracts, generally with natural origin, with lower intrinsic toxicity and a reduced negative environmental impact. In this work, polyphenolic extracts from vegetable no food/feed residues of typical Mediterranean crops, as Olea europaea, Cynara scolymus, and Vitis vinifera were obtained and their inhibitory activity on the Type Three Secretion System (TTSS) and the Quorum Sensing (QS) of the Gram-negative phytopathogenic bacterium Pseudomonas savastanoi pv. nerii strain Psn23 was assessed. Extract from green tea (Camellia sinensis) was used as a positive control. Collectively, the data obtained through gfp-promoter fusion system and real-time PCR show that all the polyphenolic extracts here studied have a high inhibitory activity on both the TTSS and QS of Psn23, without any depressing effect on bacterial viability. Extracts from green tea and grape seeds were shown to be the most active. Such activity was confirmed in planta by a strong reduction in the ability of Psn23 to develop hyperplastic galls on explants from adult oleander plants, as well as to elicit hypersensitive response on tobacco. By using a newly developed Congo red assay and an ELISA test, we demonstrated that the TTSS-targeted activity of these polyphenolic extracts also affects the TTSS pilus assembly. In consideration of the potential application of polyphenolic extracts in plant protection, the absence of any toxicity of these polyphenolic compounds was also assessed. A widely and evolutionary conserved molecular target such as Ca2+-ATPase, essential for the survival of any living organism, was used for the toxicity assessment.

No MeSH data available.


Related in: MedlinePlus

Pathogenicity test with Psn23 on oleander explants, following treatment with polyphenolic extracts VN, TV, FO or FC.Explants from adult oleander plants were inoculated with P. savastanoi pv. nerii strain Psn23, in the presence or absence of the VN, TV, FO or FC extracts (100 μM). As negative control the non pathogenic mutant ∆hrpA was used. (A) Development of hyperplastic knots at 21 dpi with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. The symptoms are detectable as swelling at the inoculated end of oleander explants. (B) Normalized weight increase of oleander explants at 21 dpi inoculated with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. Values are means ± SD of nine replicates for each treatment. Different letters indicate significant differences among means at P < 0.05, according to Tukey's test.
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pone.0163357.g001: Pathogenicity test with Psn23 on oleander explants, following treatment with polyphenolic extracts VN, TV, FO or FC.Explants from adult oleander plants were inoculated with P. savastanoi pv. nerii strain Psn23, in the presence or absence of the VN, TV, FO or FC extracts (100 μM). As negative control the non pathogenic mutant ∆hrpA was used. (A) Development of hyperplastic knots at 21 dpi with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. The symptoms are detectable as swelling at the inoculated end of oleander explants. (B) Normalized weight increase of oleander explants at 21 dpi inoculated with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. Values are means ± SD of nine replicates for each treatment. Different letters indicate significant differences among means at P < 0.05, according to Tukey's test.

Mentions: As shown in Fig 1A, a significant difference in the symptoms development was observed following inoculation of Psn23 wild type bacteria with VN or TV. In particular, a reduction of more than half of the explant weight increase was obtained for oleander explants inoculated with Psn23 treated with VN or TV in comparison to those untreated (Fig 1B).


Global Analysis of Type Three Secretion System and Quorum Sensing Inhibition of Pseudomonas savastanoi by Polyphenols Extracts from Vegetable Residues
Pathogenicity test with Psn23 on oleander explants, following treatment with polyphenolic extracts VN, TV, FO or FC.Explants from adult oleander plants were inoculated with P. savastanoi pv. nerii strain Psn23, in the presence or absence of the VN, TV, FO or FC extracts (100 μM). As negative control the non pathogenic mutant ∆hrpA was used. (A) Development of hyperplastic knots at 21 dpi with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. The symptoms are detectable as swelling at the inoculated end of oleander explants. (B) Normalized weight increase of oleander explants at 21 dpi inoculated with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. Values are means ± SD of nine replicates for each treatment. Different letters indicate significant differences among means at P < 0.05, according to Tukey's test.
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Related In: Results  -  Collection

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pone.0163357.g001: Pathogenicity test with Psn23 on oleander explants, following treatment with polyphenolic extracts VN, TV, FO or FC.Explants from adult oleander plants were inoculated with P. savastanoi pv. nerii strain Psn23, in the presence or absence of the VN, TV, FO or FC extracts (100 μM). As negative control the non pathogenic mutant ∆hrpA was used. (A) Development of hyperplastic knots at 21 dpi with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. The symptoms are detectable as swelling at the inoculated end of oleander explants. (B) Normalized weight increase of oleander explants at 21 dpi inoculated with (from left to right): Psn23, ∆hrpA, Psn23+VN, Psn23+TV, Psn23+FO, Psn23+FC. Values are means ± SD of nine replicates for each treatment. Different letters indicate significant differences among means at P < 0.05, according to Tukey's test.
Mentions: As shown in Fig 1A, a significant difference in the symptoms development was observed following inoculation of Psn23 wild type bacteria with VN or TV. In particular, a reduction of more than half of the explant weight increase was obtained for oleander explants inoculated with Psn23 treated with VN or TV in comparison to those untreated (Fig 1B).

View Article: PubMed Central - PubMed

ABSTRACT

Protection of plants against bacterial diseases still mainly relies on the use of chemical pesticides, which in Europe correspond essentially to copper-based compounds. However, recently plant diseases control is oriented towards a rational use of molecules and extracts, generally with natural origin, with lower intrinsic toxicity and a reduced negative environmental impact. In this work, polyphenolic extracts from vegetable no food/feed residues of typical Mediterranean crops, as Olea europaea, Cynara scolymus, and Vitis vinifera were obtained and their inhibitory activity on the Type Three Secretion System (TTSS) and the Quorum Sensing (QS) of the Gram-negative phytopathogenic bacterium Pseudomonas savastanoi pv. nerii strain Psn23 was assessed. Extract from green tea (Camellia sinensis) was used as a positive control. Collectively, the data obtained through gfp-promoter fusion system and real-time PCR show that all the polyphenolic extracts here studied have a high inhibitory activity on both the TTSS and QS of Psn23, without any depressing effect on bacterial viability. Extracts from green tea and grape seeds were shown to be the most active. Such activity was confirmed in planta by a strong reduction in the ability of Psn23 to develop hyperplastic galls on explants from adult oleander plants, as well as to elicit hypersensitive response on tobacco. By using a newly developed Congo red assay and an ELISA test, we demonstrated that the TTSS-targeted activity of these polyphenolic extracts also affects the TTSS pilus assembly. In consideration of the potential application of polyphenolic extracts in plant protection, the absence of any toxicity of these polyphenolic compounds was also assessed. A widely and evolutionary conserved molecular target such as Ca2+-ATPase, essential for the survival of any living organism, was used for the toxicity assessment.

No MeSH data available.


Related in: MedlinePlus