Root surface phosphatase activities and uptake of 32P-labelled inositol phosphate in field-collected gray birch and red maple roots |
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Authors: | R K Antibus Debra Bower John Dighton |
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Institution: | (1) Department of Science, Bluffton College, Bluffton, OH 45817, USA, US;(2) 904 Windbrooke Drive, Gaithersburg, MD 20879, USA, US;(3) Department of Biology, Rutgers University, Camden, NJ 08102, USA, US |
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Abstract: | This study examined select, naturally-occurring tree mycorrhizae for differences related to efficiency of organic phosphorus
hydrolysis in forest soils. We investigated the activity of several phosphatases and root respiration in field-collected ectomycorrhizae
of American beech and gray birch and VAM of red maple. Root materials were collected in the early and late growing season
from a common soil type. American beech occurred in a late-successional stand, whereas gray birch and red maple grew in a
mid-successional stand. All of the root types examined had phosphatase activities with p-nitrophenyl phosphate, bis-p-nitrophenyl phosphate and phytic acid and thus the potential to mineralize monoester and diester forms of organic phosphorus.
Rates of hydrolysis at pH 5.0 were greatest with p-nitrophenyl phosphate. Although enzyme activity varied with season and ectomycorrhizal morphotype, VAM roots of red maple
consistently had the lowest enzyme activities on a length and dry weight basis. Comparison of 32P uptake from inositol phosphate by gray birch and red maple roots suggested that phosphomonoesterase activity was linked
to P uptake from this source. Differences between species in oxygen consumption rates were less pronounced than those observed
for enzymatic activities, suggesting similar short-term energy demands by the root types examined. The quantitative differences
observed between plants growing on a common soil potentially relate to differences in host demand or reflect differences in
basic morphology and/or physiology of associated mycobionts. Further study is necessary to understand the importance of these
enzymes in the functional ecology of mycorrhizal fungi.
Accepted: 20 December 1996 |
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Keywords: | Acid phosphatase Ectomycorrhizae Phytase Phosphorus uptake Root respiration Vesicular-arbuscular mycorrhizae |
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