Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy
To study colonization of the tomato root system, we previously have described a gnotobiotic quartz sand system, in which seedlings inoculated with one or two bacterial strains were allowed to grow. Here we present a scanning electron microscope description of the colonization of the tomato root syst...
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
1997-01-01
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| Series: | Molecular Plant-Microbe Interactions |
| Subjects: | |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI.1997.10.1.79 |
| _version_ | 1831672677183520768 |
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| author | Thomas F. C. Chin-A-Woeng Wessel de Priester Arjan J. van der Bij Ben J. J. Lugtenberg |
| author_facet | Thomas F. C. Chin-A-Woeng Wessel de Priester Arjan J. van der Bij Ben J. J. Lugtenberg |
| author_sort | Thomas F. C. Chin-A-Woeng |
| collection | DOAJ |
| description | To study colonization of the tomato root system, we previously have described a gnotobiotic quartz sand system, in which seedlings inoculated with one or two bacterial strains were allowed to grow. Here we present a scanning electron microscope description of the colonization of the tomato root system by Pseudomonas fluorescens biocontrol strain WCS365, with emphasis on spatial-temporal colonization patterns, based on an improved scanning electron microscopy procedure. Upon inoculation of the germinated seed, proliferation on the seed coat was observed for 2 to 3 days. Within 1 to 3 days, micro-colonies developed, mainly at the root base. Most micro-colonies were localized in junctions between epidermal root cells, whereas others were found in indented parts of the epidermal surface. Downward to the root tip, only single bacterial cells were found. Colonization progressed down the root, initially as single cells. A semi-transparent film appeared to enclose the root surface and micro-colonies present on the root. After 7 days, micro-colonies had developed at positions where only single cells were observed previously and distribution of the bacteria along the root varied from ≈106 CFU per cm of root near the root base to ≈102 to 103 CFU per cm of root near the root tip. Similar colonization patterns were found for the P. fluorescens biocontrol strains CHA0 and F113, and P. putida strain WCS358, as well as for four species that have repeatedly been isolated from tomato roots from a commercial tomato field near Granada, Spain. In contrast, four Rhizobium strains and one Acinetobacter radioresistens strain showed poor colonization and micro-colonies were not observed. Based on the described data, we present a model for colonization of the deeper root parts after seed inoculation by P. fluorescens biocontrol strains, in which single cells occasionally establish on a deeper root section where they sometimes develop into micro-colonies. We hypothesize that micro-colonies are the sites where the intracellular N-acyl-L-homoserine lactone concentration is sufficiently high to cause maximal production of biocontrol factors such as antibiotics and exoenzymes and that micro-colonies explain the relatively high conjugation frequency observed between pseudomonads in the rhizosphere. |
| first_indexed | 2024-12-19T23:56:54Z |
| format | Article |
| id | doaj.art-f50e10382eed45d48896733a89f39aa7 |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-12-19T23:56:54Z |
| publishDate | 1997-01-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-f50e10382eed45d48896733a89f39aa72022-12-21T20:00:59ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77061997-01-01101798610.1094/MPMI.1997.10.1.79Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron MicroscopyThomas F. C. Chin-A-WoengWessel de PriesterArjan J. van der BijBen J. J. LugtenbergTo study colonization of the tomato root system, we previously have described a gnotobiotic quartz sand system, in which seedlings inoculated with one or two bacterial strains were allowed to grow. Here we present a scanning electron microscope description of the colonization of the tomato root system by Pseudomonas fluorescens biocontrol strain WCS365, with emphasis on spatial-temporal colonization patterns, based on an improved scanning electron microscopy procedure. Upon inoculation of the germinated seed, proliferation on the seed coat was observed for 2 to 3 days. Within 1 to 3 days, micro-colonies developed, mainly at the root base. Most micro-colonies were localized in junctions between epidermal root cells, whereas others were found in indented parts of the epidermal surface. Downward to the root tip, only single bacterial cells were found. Colonization progressed down the root, initially as single cells. A semi-transparent film appeared to enclose the root surface and micro-colonies present on the root. After 7 days, micro-colonies had developed at positions where only single cells were observed previously and distribution of the bacteria along the root varied from ≈106 CFU per cm of root near the root base to ≈102 to 103 CFU per cm of root near the root tip. Similar colonization patterns were found for the P. fluorescens biocontrol strains CHA0 and F113, and P. putida strain WCS358, as well as for four species that have repeatedly been isolated from tomato roots from a commercial tomato field near Granada, Spain. In contrast, four Rhizobium strains and one Acinetobacter radioresistens strain showed poor colonization and micro-colonies were not observed. Based on the described data, we present a model for colonization of the deeper root parts after seed inoculation by P. fluorescens biocontrol strains, in which single cells occasionally establish on a deeper root section where they sometimes develop into micro-colonies. We hypothesize that micro-colonies are the sites where the intracellular N-acyl-L-homoserine lactone concentration is sufficiently high to cause maximal production of biocontrol factors such as antibiotics and exoenzymes and that micro-colonies explain the relatively high conjugation frequency observed between pseudomonads in the rhizosphere.https://apsjournals.apsnet.org/doi/10.1094/MPMI.1997.10.1.79microbiological controlrhizosphere colonization |
| spellingShingle | Thomas F. C. Chin-A-Woeng Wessel de Priester Arjan J. van der Bij Ben J. J. Lugtenberg Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy Molecular Plant-Microbe Interactions microbiological control rhizosphere colonization |
| title | Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy |
| title_full | Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy |
| title_fullStr | Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy |
| title_full_unstemmed | Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy |
| title_short | Description of the Colonization of a Gnotobiotic Tomato Rhizosphere by Pseudomonas fluorescens Biocontrol Strain WCS365, Using Scanning Electron Microscopy |
| title_sort | description of the colonization of a gnotobiotic tomato rhizosphere by pseudomonas fluorescens biocontrol strain wcs365 using scanning electron microscopy |
| topic | microbiological control rhizosphere colonization |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI.1997.10.1.79 |
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