Effects of Light and Darkness on Biosynthesis of Carotenoid Pigments in Wheat Seedlings

The seeds of most higher plants contain relatively small quantities of carotenoid pigments. Upon germination and early seedling growth in the absence of light, more carotenoids are synthesized. Both in seeds (4) and in dark-grown seedlings (3, 14, 2), the carotenoid fraction has been found to consist principally of xanthophylls, with carotenes being present in much smaller amounts. The biosynthesis of carotenoid pigments, w-hich can occur in total darkness, is greatly stimulated in light, much of the increase occurring in the carotene fraction (1, 2). The role of light in carotenoid biosynthesis has been studied intensively in a variety of plant materials by earlier investigators (10, 11, 7, 5). The study of Kay and Phinney (7) with corn indicated that lutein was the major constituent of darkgrown seedlings. On illumination, large increases occurred in 8-carotene and neo ,8-carotene. In French bean, Phaseolus vulgaris, Goodwin and Phagpolngarm (5) observed large increases in /3carotene and lutein in both cotyledons and leaves upon illumination of dark grown plants. It is the purpose of this paper to present the results of analyses of the carotenoid pigments of wheat seedlings grown in light and in darkness.