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A Carotenoid-Deficient Mutant in Pantoea sp. YR343, a Bacteria Isolated from the Rhizosphere of Populus deltoides, Is Defective in Root Colonization.

Bible AN, Fletcher SJ, Pelletier DA, Schadt CW, Jawdy SS, Weston DJ, Engle NL, Tschaplinski T, Masyuko R, Polisetti S, Bohn PW, Coutinho TA, Doktycz MJ, Morrell-Falvey JL - Front Microbiol (2016)

Bottom Line: The complex interactions between plants and their microbiome can have a profound effect on the health and productivity of the plant host.Finally we demonstrate that the ΔcrtB mutant shows reduced colonization of plant roots.YR343.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA.

ABSTRACT
The complex interactions between plants and their microbiome can have a profound effect on the health and productivity of the plant host. A better understanding of the microbial mechanisms that promote plant health and stress tolerance will enable strategies for improving the productivity of economically important plants. Pantoea sp. YR343 is a motile, rod-shaped bacterium isolated from the roots of Populus deltoides that possesses the ability to solubilize phosphate and produce the phytohormone indole-3-acetic acid (IAA). Pantoea sp. YR343 readily colonizes plant roots and does not appear to be pathogenic when applied to the leaves or roots of selected plant hosts. To better understand the molecular mechanisms involved in plant association and rhizosphere survival by Pantoea sp. YR343, we constructed a mutant in which the crtB gene encoding phytoene synthase was deleted. Phytoene synthase is responsible for converting geranylgeranyl pyrophosphate to phytoene, an important precursor to the production of carotenoids. As predicted, the ΔcrtB mutant is defective in carotenoid production, and shows increased sensitivity to oxidative stress. Moreover, we find that the ΔcrtB mutant is impaired in biofilm formation and production of IAA. Finally we demonstrate that the ΔcrtB mutant shows reduced colonization of plant roots. Taken together, these data suggest that carotenoids are important for plant association and/or rhizosphere survival in Pantoea sp. YR343.

No MeSH data available.


Related in: MedlinePlus

Loss of carotenoids affects biofilm formation and root colonization. (A) Comparison of biofilm formation between wild type Pantoea sp. YR343 and the ΔcrtB mutant in plastic 96-well plates measured by the crystal violet assay (B) Pellicle formation assay performed in SOBG medium in glass test tubes. Wild type Pantoea sp. YR343 forms pellicles on top of the liquid medium, while the ΔcrtB mutant settles to the bottom of the tube. (C) Wheat root colonization assay by wild type Pantoea sp. YR343 and ΔcrtB is described as the Log10 value of colony forming units (CFUs) per gram of root material. (D) Images of wheat roots treated with YR343-GFP and ΔcrtB for 1 week and stained with Syto61. Top left image shows a group of motile cells outside of the plant. Green represents the wild type population, while red represents the ΔcrtB mutant population. Top right image shows a wheat root (visualized using autofluorescence in the red channel) colonized predominantly by wild typeYR343-GFP (green). Bottom image shows a three-dimensional view of a colonized wheat root.
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Figure 6: Loss of carotenoids affects biofilm formation and root colonization. (A) Comparison of biofilm formation between wild type Pantoea sp. YR343 and the ΔcrtB mutant in plastic 96-well plates measured by the crystal violet assay (B) Pellicle formation assay performed in SOBG medium in glass test tubes. Wild type Pantoea sp. YR343 forms pellicles on top of the liquid medium, while the ΔcrtB mutant settles to the bottom of the tube. (C) Wheat root colonization assay by wild type Pantoea sp. YR343 and ΔcrtB is described as the Log10 value of colony forming units (CFUs) per gram of root material. (D) Images of wheat roots treated with YR343-GFP and ΔcrtB for 1 week and stained with Syto61. Top left image shows a group of motile cells outside of the plant. Green represents the wild type population, while red represents the ΔcrtB mutant population. Top right image shows a wheat root (visualized using autofluorescence in the red channel) colonized predominantly by wild typeYR343-GFP (green). Bottom image shows a three-dimensional view of a colonized wheat root.

Mentions: We next examined the ability of wild type and ΔcrtB cells to form biofilms using two different formats: biofilm formation on abiotic surfaces using 96-well plates with breathable tape, and biofilm formation at the air-liquid interface (pellicles) using glass test tubes. Using the 96-well plate assay, we found that the ΔcrtB mutant was impaired in biofilm formation, with the defect more apparent when cells were grown in LB medium (Figure 6A). Likewise, ΔcrtB mutant cells were also impaired in pellicle formation (Figure 6B). In this experiment, the mutant cells tended to settle at the bottom of the tube rather than form a biofilm at the air-liquid interface like wild type cells.


A Carotenoid-Deficient Mutant in Pantoea sp. YR343, a Bacteria Isolated from the Rhizosphere of Populus deltoides, Is Defective in Root Colonization.

Bible AN, Fletcher SJ, Pelletier DA, Schadt CW, Jawdy SS, Weston DJ, Engle NL, Tschaplinski T, Masyuko R, Polisetti S, Bohn PW, Coutinho TA, Doktycz MJ, Morrell-Falvey JL - Front Microbiol (2016)

Loss of carotenoids affects biofilm formation and root colonization. (A) Comparison of biofilm formation between wild type Pantoea sp. YR343 and the ΔcrtB mutant in plastic 96-well plates measured by the crystal violet assay (B) Pellicle formation assay performed in SOBG medium in glass test tubes. Wild type Pantoea sp. YR343 forms pellicles on top of the liquid medium, while the ΔcrtB mutant settles to the bottom of the tube. (C) Wheat root colonization assay by wild type Pantoea sp. YR343 and ΔcrtB is described as the Log10 value of colony forming units (CFUs) per gram of root material. (D) Images of wheat roots treated with YR343-GFP and ΔcrtB for 1 week and stained with Syto61. Top left image shows a group of motile cells outside of the plant. Green represents the wild type population, while red represents the ΔcrtB mutant population. Top right image shows a wheat root (visualized using autofluorescence in the red channel) colonized predominantly by wild typeYR343-GFP (green). Bottom image shows a three-dimensional view of a colonized wheat root.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834302&req=5

Figure 6: Loss of carotenoids affects biofilm formation and root colonization. (A) Comparison of biofilm formation between wild type Pantoea sp. YR343 and the ΔcrtB mutant in plastic 96-well plates measured by the crystal violet assay (B) Pellicle formation assay performed in SOBG medium in glass test tubes. Wild type Pantoea sp. YR343 forms pellicles on top of the liquid medium, while the ΔcrtB mutant settles to the bottom of the tube. (C) Wheat root colonization assay by wild type Pantoea sp. YR343 and ΔcrtB is described as the Log10 value of colony forming units (CFUs) per gram of root material. (D) Images of wheat roots treated with YR343-GFP and ΔcrtB for 1 week and stained with Syto61. Top left image shows a group of motile cells outside of the plant. Green represents the wild type population, while red represents the ΔcrtB mutant population. Top right image shows a wheat root (visualized using autofluorescence in the red channel) colonized predominantly by wild typeYR343-GFP (green). Bottom image shows a three-dimensional view of a colonized wheat root.
Mentions: We next examined the ability of wild type and ΔcrtB cells to form biofilms using two different formats: biofilm formation on abiotic surfaces using 96-well plates with breathable tape, and biofilm formation at the air-liquid interface (pellicles) using glass test tubes. Using the 96-well plate assay, we found that the ΔcrtB mutant was impaired in biofilm formation, with the defect more apparent when cells were grown in LB medium (Figure 6A). Likewise, ΔcrtB mutant cells were also impaired in pellicle formation (Figure 6B). In this experiment, the mutant cells tended to settle at the bottom of the tube rather than form a biofilm at the air-liquid interface like wild type cells.

Bottom Line: The complex interactions between plants and their microbiome can have a profound effect on the health and productivity of the plant host.Finally we demonstrate that the ΔcrtB mutant shows reduced colonization of plant roots.YR343.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA.

ABSTRACT
The complex interactions between plants and their microbiome can have a profound effect on the health and productivity of the plant host. A better understanding of the microbial mechanisms that promote plant health and stress tolerance will enable strategies for improving the productivity of economically important plants. Pantoea sp. YR343 is a motile, rod-shaped bacterium isolated from the roots of Populus deltoides that possesses the ability to solubilize phosphate and produce the phytohormone indole-3-acetic acid (IAA). Pantoea sp. YR343 readily colonizes plant roots and does not appear to be pathogenic when applied to the leaves or roots of selected plant hosts. To better understand the molecular mechanisms involved in plant association and rhizosphere survival by Pantoea sp. YR343, we constructed a mutant in which the crtB gene encoding phytoene synthase was deleted. Phytoene synthase is responsible for converting geranylgeranyl pyrophosphate to phytoene, an important precursor to the production of carotenoids. As predicted, the ΔcrtB mutant is defective in carotenoid production, and shows increased sensitivity to oxidative stress. Moreover, we find that the ΔcrtB mutant is impaired in biofilm formation and production of IAA. Finally we demonstrate that the ΔcrtB mutant shows reduced colonization of plant roots. Taken together, these data suggest that carotenoids are important for plant association and/or rhizosphere survival in Pantoea sp. YR343.

No MeSH data available.


Related in: MedlinePlus