Abstract
A comparison was made of water-soluble root exudates and extracts of Sorghum vulgare Pers. grown under two levels of P nutrition. An increase in P nutrition significantly decreased the concentration of carbohydrates, carboxylic acids, and amino acids in exudates, and decreased the concentration of carboxylic acids in extracts. Higher P did not affect the relative proportions of specific carboxylic acids and had little effect on proportions of specific amino acids in both extracts and exudates. Phosphorus amendment resulted in an increase in the relative proportion of arabinose and a decrease in the proportion of fructose in exudates, but did not have a large effect on the proportion of individual sugars in extracts. The proportions of specific carbohydrates, carboxylic acids, and amino acids varied between exudates and extracts. Therefore, the quantity and composition of root extracts may not be a reliable predictor of the availability of substrate for symbiotic vesicular-arbuscular mycorrhizal fungi. Comparisons of the rate of leakage of compounds from roots with the growth rate of vesicular-arbuscular mycorrhizal fungi suggest that the fungus must either be capable of using a variety of organic substrates for growth, or be capable of inducing a much higher rate of movement of specific organic compounds across root cell membranes than occurs through passive exudation as measured in this study.
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Selected References
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- Graham J. H., Leonard R. T., Menge J. A. Membrane-mediated decrease in root exudation responsible for phorphorus inhibition of vesicular-arbuscular mycorrhiza formation. Plant Physiol. 1981 Sep;68(3):548–552. doi: 10.1104/pp.68.3.548. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morris D. L. Quantitative Determination of Carbohydrates With Dreywood's Anthrone Reagent. Science. 1948 Mar 5;107(2775):254–255. doi: 10.1126/science.107.2775.254. [DOI] [PubMed] [Google Scholar]
- Richter M., Wilms W., Scheffer F. Determination of Root Exudates in a Steril Continuous Flow Culture. II. Short-Term and Long-Term Variations of Exudation Intensity. Plant Physiol. 1968 Nov;43(11):1747–1754. doi: 10.1104/pp.43.11.1747. [DOI] [PMC free article] [PubMed] [Google Scholar]