REDUCTION IN THE LEVEL OF INTRACELLULAR MYOINOSITOL IN CULTURED SOYBEAN (GLYCINE MAX) CELLS INHIBITS CELL-DIVISION

Although myo-inositol is included in media for the successful growth of plant tissues, the actual requirement of most tissues, including soybean (Glycine max) callus in suspension culture, for myo-inositol has not been demonstrated. We have made use of deoxyglucose to reduce intracellular levels of myo-inositol. Deoxyglucose is phosphorylated to deoxyglucose 6-phosphate, which inhibits L-myo-inositol 1-phosphate synthase, an important enzyme in the synthesis of myo-inositol. Addition of deoxyglucose to the medium resulted in a decrease in the intracellular level of myo-inositol that corresponded with a decrease in cell division. Cell viability was not affected. When myo-inositol was added to cells along with deoxyglucose, cell division was restored, as were intracellular levels of myo-inositol. Addition of myo-inositol had no affect on the uptake or metabolism of deoxyglucose. From these results we propose that myo-inositol has a role in maintaining cell division in soybean callus tissue in suspension culture.