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THE MECHANISM OF ABSORPTION AND UTILIZATION OF PHOSPHATE BY BARLEY PLANTS IN RELATION TO SUBSEQUENT TRANSPORT TO THE SHOOT
Author(s) -
LOUGHMAN B. C.
Publication year - 1966
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1966.tb06375.x
Subject(s) - phosphate , shoot , hexose , mannose , metabolism , chemistry , phosphorus , biochemistry , absorption (acoustics) , sugar phosphates , biology , botany , enzyme , organic chemistry , physics , acoustics
S ummary An attempt has been made to distinguish between the process of absorption of orthophosphate by the roots of whole barley plants and that of subsequent transport to the shoot. Such selection can be induced by treatment with growth regulators and inhibitors of specific biochemical stages in phosphorus metabolism. The presence of physiological concentrations of D‐mannose in the root environment has little effect on the overall uptake of radioactive phosphate. The metabolic fate of the absorbed phosphate is, however, severely affected and the ion appears to be reversibly sequestered in the form of hexose monophosphates other than those found to be labelled under normal conditions. Both glucose‐1 ‐phosphate and mannose‐6‐phosphate contain radioactive phosphorus after treatment with mannose. Although overall uptake is relatively unaffected, mannose specifically inhibits further transport of the metabolized phosphate to the shoot and it is concluded that this transport is directly dependent on the prior incorporation of the incoming phosphate into a specific sequence of organic compounds. The results are discussed in relation to the possible mechanisms involved in the separate processes of absorption and transport.