Respiratory responses of arbuscular mycorrhizal roots to short-term alleviation of P deficiency |
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Authors: | A J Valentine A Kleinert |
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Institution: | (1) Department of Horticulture, Applied Sciences Faculty, Cape Peninsula University of Technology, P.O. Box 652, Cape Town, 8000, South Africa |
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Abstract: | Arbuscular mycorrhizal (AM) root respiration can impose a respiratory sink on host reserves under low P conditions, but it
is not known how AM roots respond to short-term supply of sufficient P. Therefore, the effect of P stress alleviation on the
respiration of AM roots was investigated in 5-week-old tomato plants. Plants were inoculated with Glomus mosseae in sand culture and grown hydroponically in a low P (2 μM) nutrient medium for 3 weeks. P stress was alleviated by the supply
of 2 mM P for 72 h. With P stress alleviation, the improved root P status coincided with a decline in AM fungal activity and
a reduction in root CO2 and O2 fluxes of the AM plants. During P stress alleviation, the AM roots had lower concentrations of organic acids, derived from
root-zone CO2 assimilation, in their root exudates. These results show that short-term alleviation of low P conditions in AM roots rapidly
affects AM fungal symbiont activity, AM root respiration, and root-zone CO2-derived organic acid metabolism. |
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Keywords: | Arbuscular mycorrhiza P stress Respiration Organic acids |
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