On the nature of the precursor of the vitamin C in the vegetable kingdom

Publisher Website
Google Scholar
Abstract
The amt. of ascorbic acid (AA) in pea seedlings germinated naturally rose for 2 days and then reached a constant conc. of 0.5 mgm. of the acid per gm. of the wet wt. of the seedlings. Embryo seedlings from peas, excised from the cotyledons and grown on nutrient gelatin containing hexoses, synthesized a large amt. of AA. Of the 4 hexoses examined, mannose gave the highest figure, 0.5 mgm. of AA per gm. seedling. Disaccharides also gave moderately high figures but all other substances examined either gave very low or absolutely neg. values. Hexoses may serve as precursors of vit. C in germinating seeds. The rate of production of AA in the cultivated excised seedlings bore no direct relation to the rate of growth, e.g., seedlings grown on mannose showed very little growth but had a high conc. of AA, while arabinose and xylose seemed to favor growth but production of AA was nil. The conc. of AA present per gm. in the excised seedlings fell steadily during prolonged periods of cultivation. The conc. of AA formed was ca. proportional to the conc. of the substrate up to a certain opt. value, after which it remained constant. Unsuccessful at pl. ts were made to produce good growth combined with large production of AA by cultivated excised seedlings on a medium containing a mixture of 2 substances, one found to favor growth and the other production of AA.