Myo-inositol Biosynthesis and Galactose Utilization by Wild Carrot (Daucus carota L. var. carota) Suspension Cultures

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Abstract
Wild carrot (Daucus carota var. carota) cell suspensions (63–120 μm in diameter) were grown on a mineral salt medium containing different carbon sources in the presence (10 mM) and absence of myo-inositol. The data obtained after 14 and 21 days of growth show that an external supply of myo-inositol is not essential for growth and development of wild carrot embryos. A linear relationship was found between growth (d. wt) and embryo number in the presence and absence of myo-inositol. Standard stock cell suspensions never exposed to exogenous myo-inositol and grown in the absence of 2, 4-D with glucose or galactose as the carbon source synthesized radioactive myo-inositol when exposed to D-[1–14C]glucose or D-[1–14C]galactose. Gas chromatographic analyses revealed the presence of myo-inositol in the bulk tissue grown in the presence of 2.25 μM 2, 4-D with glucose, galactose, fructose or mannose as the sole carbohydrate. We could not detect any component indicating an isomer or a methylated derivative of an inositol in the tissue extracts. Stock cultures were maintained (with 2, 4-D) successfully for at least three successive sub-cultures on D-galactose as the sole carbohydrate. The growth achieved over this culture period showed that wild carrot cells used by us could quickly adapt to grow on D-galactose as rapidly as they grow on sucrose.