FORMATION OF MYO-INOSITOL AND PHYTIN IN RIPENING RICE GRAINS

概要

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With the view to elucidate the role of myo-inositol in the ripening process of rice grains, its distribution, formation and conversion were studied. 1. myo-Inositol in the ripening rice grains was fractionated into free-, phosphate ester- and phosphoinositide-forms. At the early stage of ripening, a considerable part of myo-inositol was found in free state, and at the end of ripening stage the most part was found in phosphate ester-state, phytic acid. The content of phosphoinositide in the grains was low during the ripening period. 2. The occurrence of biosynthesis of myo-inositol in the ripening rice grains was confirmed by the observation of incorporation of ^<14>C into myo-inositol from ^<14>C-sugars, and it was found, from the feeding experiment of myo-inositol-^3H, that myo-inositol does not undergo reactions further than phosphorylation. 3. The feeding experiment of glucose-l-^<32>P showed that the distribution pattern of ^<32>P in different fractions of grain material was the same as that of ^<32>P-phosphate, indicating that phytic acid is one of the final products of phosphorus metabolism in the ripening rice grains. 4. These results led to the assumption that myo-inositol might act as an acceptor of phosphorus to remove inorganic phosphorus in favor of starch synthesis by phosphorylase.
日本植物生理学会の論文