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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

Colonization of plant roots by Pantoea sp. YR343. (A)Arabidopsis thaliana plants were grown on MS plates in the absence or presence of Pantoea sp. YR343 for 10 days prior to imaging. (B) Corresponding to the pictures in (A) are images of roots taken with confocal microscopy. The image on top shows roots from an uninoculated plant, while the bottom image shows roots colonized by YR343-pGFP. (C)Populus deltoides WV94 cuttings were grown in the presence or absence of Panteoa sp. YR343 expressing GFP. (Top) untreated P. deltoides WV94 plant; (bottom) P. deltoides WV94 cultured with YR343-pGFP for 7 days. In all images, Pantoea sp. YR343 is detected by GFP fluorescence (green) and plant roots are detected using autofluorescence (red).
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Figure 3: Colonization of plant roots by Pantoea sp. YR343. (A)Arabidopsis thaliana plants were grown on MS plates in the absence or presence of Pantoea sp. YR343 for 10 days prior to imaging. (B) Corresponding to the pictures in (A) are images of roots taken with confocal microscopy. The image on top shows roots from an uninoculated plant, while the bottom image shows roots colonized by YR343-pGFP. (C)Populus deltoides WV94 cuttings were grown in the presence or absence of Panteoa sp. YR343 expressing GFP. (Top) untreated P. deltoides WV94 plant; (bottom) P. deltoides WV94 cultured with YR343-pGFP for 7 days. In all images, Pantoea sp. YR343 is detected by GFP fluorescence (green) and plant roots are detected using autofluorescence (red).

Mentions: We next analyzed the ability of Pantoea sp. YR343 to colonize plant surfaces. Co-cultures of Arabidopsis seedlings and Pantoea sp. YR343 showed that seedlings grown in the presence of the microbe had enhanced lateral root density compared to control seedlings (Figure 3A). To enable detection of Panteoa sp. YR343 on plant roots, we constructed a fluorescent strain (YR343-pGFP) in which GFP was expressed from a Gateway-modified pBBR1 plasmid (Pelletier et al., 2008). Using this fluorescent strain, we found that YR343-pGFP readily attached to the surface of Arabidopsis roots (Figure 3B). The same fluorescent strain was then used to determine whether Pantoea associated directly with Populus roots. Sterile P. deltoides WV94 cuttings were exposed to YR343-pGFP at the roots by inoculation into the soil at a concentration of 2.7 × 107 CFU g-1 of soil. YR343-pGFP was re-isolated from the roots and soil at day 7 to determine its distribution and confirm viability on plants and in the soil. Pantoea sp. YR343 was preferentially associated with the plant as indicated by 3.5 × 106 CFU g-1 of root, compared to 3.0 × 102 CFU g-1 of soil. Consistent with this data, we observed YR343-pGFP cells attached to P. deltoides roots using confocal microscopy, whereas no bacteria were detected in the un-inoculated control plants (Figure 3C). Indeed, numerous locations along the roots were covered in bacteria. The bacteria were aggregated into what appeared to be biofilms on the surface of the roots and along the root hairs. Because the roots underwent several washes when they were harvested, the bacteria colonizing the Populus roots were firmly attached, as the transiently attached cells were presumably washed away.


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)

Colonization of plant roots by Pantoea sp. YR343. (A)Arabidopsis thaliana plants were grown on MS plates in the absence or presence of Pantoea sp. YR343 for 10 days prior to imaging. (B) Corresponding to the pictures in (A) are images of roots taken with confocal microscopy. The image on top shows roots from an uninoculated plant, while the bottom image shows roots colonized by YR343-pGFP. (C)Populus deltoides WV94 cuttings were grown in the presence or absence of Panteoa sp. YR343 expressing GFP. (Top) untreated P. deltoides WV94 plant; (bottom) P. deltoides WV94 cultured with YR343-pGFP for 7 days. In all images, Pantoea sp. YR343 is detected by GFP fluorescence (green) and plant roots are detected using autofluorescence (red).
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Figure 3: Colonization of plant roots by Pantoea sp. YR343. (A)Arabidopsis thaliana plants were grown on MS plates in the absence or presence of Pantoea sp. YR343 for 10 days prior to imaging. (B) Corresponding to the pictures in (A) are images of roots taken with confocal microscopy. The image on top shows roots from an uninoculated plant, while the bottom image shows roots colonized by YR343-pGFP. (C)Populus deltoides WV94 cuttings were grown in the presence or absence of Panteoa sp. YR343 expressing GFP. (Top) untreated P. deltoides WV94 plant; (bottom) P. deltoides WV94 cultured with YR343-pGFP for 7 days. In all images, Pantoea sp. YR343 is detected by GFP fluorescence (green) and plant roots are detected using autofluorescence (red).
Mentions: We next analyzed the ability of Pantoea sp. YR343 to colonize plant surfaces. Co-cultures of Arabidopsis seedlings and Pantoea sp. YR343 showed that seedlings grown in the presence of the microbe had enhanced lateral root density compared to control seedlings (Figure 3A). To enable detection of Panteoa sp. YR343 on plant roots, we constructed a fluorescent strain (YR343-pGFP) in which GFP was expressed from a Gateway-modified pBBR1 plasmid (Pelletier et al., 2008). Using this fluorescent strain, we found that YR343-pGFP readily attached to the surface of Arabidopsis roots (Figure 3B). The same fluorescent strain was then used to determine whether Pantoea associated directly with Populus roots. Sterile P. deltoides WV94 cuttings were exposed to YR343-pGFP at the roots by inoculation into the soil at a concentration of 2.7 × 107 CFU g-1 of soil. YR343-pGFP was re-isolated from the roots and soil at day 7 to determine its distribution and confirm viability on plants and in the soil. Pantoea sp. YR343 was preferentially associated with the plant as indicated by 3.5 × 106 CFU g-1 of root, compared to 3.0 × 102 CFU g-1 of soil. Consistent with this data, we observed YR343-pGFP cells attached to P. deltoides roots using confocal microscopy, whereas no bacteria were detected in the un-inoculated control plants (Figure 3C). Indeed, numerous locations along the roots were covered in bacteria. The bacteria were aggregated into what appeared to be biofilms on the surface of the roots and along the root hairs. Because the roots underwent several washes when they were harvested, the bacteria colonizing the Populus roots were firmly attached, as the transiently attached cells were presumably washed away.

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