NIACIN BIOSYNTHESIS IN GERMINATING×LAELIOCATTLEYA ORCHID EMBRYOS AND YOUNG SEEDLINGS |
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| Authors: | Joseph Arditti |
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| Institution: | Department of Organismic Biology, University of California, Irvine |
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| Abstract: | The roles of tryptophan, kynurenne, 3-hydroxyanthranilic acid, and quinolinic acid as niacin precursors were investigated by assessing their germination and growth-promoting effects in orchid embryo and seedling cultures. Only niacin, 3-hydroxyanthranilic acid, quinolinic acid and kynurenine exhibited a growth-promoting effect on seedlings of all ages. Tryptophan inhibited the growth of 70-day-old seedlings but enhanced growth of older seedlings. The data presented are interpreted to be consistent with the hypothesis that orchids may synthesize their niacin by a pathway similar to that of certain bacteria, fungi, birds, and mammals. |
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