Use of a gnotobiotic plant assay for assessing root colonization and mineral phosphate solubilization by Paraburkholderia bryophila Ha185 in association with perennial ryegrass (Lolium perenne L.)

Aims The mechanisms by which rhizosphere bacteria increase the availability of mineral P precipitates for plant use are understudied. However, Paraburkholderia bryophila Ha185 is known to solubilize inorganic phosphate in vitro via a novel process. Therefore, this study aimed to demonstrate P solubi...

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Bibliographic Details
Published in:Plant and soil 2018-04, Vol.425 (1/2), p.43-55
Main Authors: Hsu, Pei-Chun Lisa, O'Callaghan, Maureen, Condron, Leo, Hurst, Mark R. H.
Format: Article
Language:English
Subjects:
Biological research
Biomedical and Life Sciences
Colonization
Confocal microscopy
Ecology
Fluorescence
Gnotobiotic
Gnotobiotics
Green fluorescent protein
Hydroxyapatite
Life Sciences
Lolium perenne
METHODS PAPER
Microscopy
Phosphates
Physiological aspects
Plant growth
Plant Physiology
Plant Sciences
Precipitates
Rhizoplane
Rhizosphere
Root hairs
Roots
Roots (Botany)
Ryegrasses
Soil improvement
Soil Science & Conservation
Solubilization
Turfgrasses
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Summary:Aims The mechanisms by which rhizosphere bacteria increase the availability of mineral P precipitates for plant use are understudied. However, Paraburkholderia bryophila Ha185 is known to solubilize inorganic phosphate in vitro via a novel process. Therefore, this study aimed to demonstrate P solubilization by Ha185 in association with roots of perennial ryegrass (Lolium perenne L.). Methods We developed a gnotobiotic plant assay to assess P solubilization by Ha185 on ryegrass roots under various nutrient conditions. A green fluorescent protein (GFP)-tagged derivative of Ha185 was used in conjunction with fluorescent microscopy and confocal microscopy to visualize colonization of ryegrass roots. Results Ha185 solubilized mineral P (hydroxyapatite) in association with ryegrass roots and increased ryegrass growth by 20% under P-limited conditions. The GFP-tagged Ha185 strain colonized the rhizoplane and penetrated the primaiy root of ryegrass, possibly through "crack entry" at the point of lateral root emergence, but also by entering the epidermal cells via root hairs. Conclusions Ha185 supported ryegrass growth under P-limited conditions, indicating this strain may improve availability of soil P for uptake by ryegrass. Tools developed in this study have broad application in the study of rhizobacteria-plant interactions.
ISSN:0032-079X
1573-5036
DOI:10.1007/s11104-018-3633-6