Linking the depletion of rhizosphere phosphorus to the heterologous expression of a fungal phytase in Nicotiana tabacum as revealed by enzyme-labile P and solution 31P NMR spectroscopy

Giles, Courtney D. and George, Timothy S. and Brown, Lawrie K. and Mezeli, Malika and Shand, Charles A. and Richardson, Alan E. and Mackay, Regina and Wendler, Renate and Darch, Tegan and Menezes-Blackburn, Daniel and Cooper, Pat and Stutter, Marc I. and Lumsdon, David G. and Blackwell, Martin S.A. and Wearing, Catherine and Zhang, Hao and Haygarth, Philip M. (2017) Linking the depletion of rhizosphere phosphorus to the heterologous expression of a fungal phytase in Nicotiana tabacum as revealed by enzyme-labile P and solution 31P NMR spectroscopy. Rhizosphere, 3 (1). pp. 82-91. ISSN 2452-2198

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Abstract

Root exudation of phytase could improve the ability of plants to access organic forms of soil phosphorus (P), thereby minimizing fertilizer requirements and improving P use efficiency in agroecosystems. After 75 days growth in a high available P soil, shoot biomass and P accumulation, soil pH, and rhizosphere P depletion were investigated in Nicotiana tabacum wild-type and transgenic plant-lines expressing and exuding Aspergillus niger phytase (ex::phyA), or a null-vector control. Solution 31P NMR analysis revealed a 7% to 11% increase in orthophosphate and a comparable depletion of undefined monoester P compounds (-13 to -18%) in the rhizosphere of tobacco plants relative to the unplanted soil control. Wild-type plants had the greatest impact on the composition of rhizosphere P based on the depletion of other monoester P, polyphosphate, and phosphonate species. The depletion of phytase-labile P by ex::phyA plants was associated with decreased proportions of other monoester P, rather than myo-InsP6 as expected. Rhizosphere pH increased from 6.0 to 6.5–6.7 in transgenic plant soils, beyond the pH optimum for A. niger phyA activity (pH=5), and may explain the limited specificity of ex::phyA plants for phytate in this soil. The efficacy of single exudation traits (e.g., phytase) therefore appear to be limited in P-replete soil conditions and may be improved where soil pH matches the functional requirements of the enzyme or trait of interest.

Item Type:
Journal Article
Journal or Publication Title:
Rhizosphere
Additional Information:
This is the author’s version of a work that was accepted for publication in Rhizosphere. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Rhizosphere, 3, 1, 2017 DOI: 10.1016/j.rhisph.2016.11.004
Subjects:
ID Code:
83560
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Deposited On:
12 Dec 2016 13:30
Refereed?:
Yes
Published?:
Published
Last Modified:
05 Jun 2020 03:32