myo-Inositol metabolism in germinating wheat.

During imbibition, exogenous myo-inositol (MI) was readily introduced into the free MI pool of germinating wheat (Triticum aestivum L.). Maximum uptake, 70 μg per caryopsis or 1.5 mg g(-1) of caryopsis, was reached at 0.05 M MI. Movement of free MI within the germinating caryopsis was traced with [2-(3)H]MI by two procedures, uptake by imbibition and injection into softened endosperm. The former procedure was useful during initial stages of germination; the latter provided a means of tracing the metabolic fate of MI generated by hydrolysis of phytate during mobilization of reserves within the caryopsis. In both procedures, the bulk of the added label was transferred to the seedling where it appeared in uronosyl and pentosyl units of 80% ethanol-insoluble polysaccharides, 2-O, C-Methylene-MI, an inhibitor of the MI oxidation pathway, blocked the utilization of [2-(3)H]MI as well as D-[1(14)C]glucose for biogenesis of pentose-and uronic-acid-containing polysaccharides.