IAA METABOLISM IN EMBRYOGENIC AND NONEMBRYOGENIC CARROT CELLS

Carrot somatic embryos can readily be induced from embryogenic cells transferred from auxin-containing medium to auxin-free medium, but not from transferred non-embryogenic cells. It is well-known that IAA, a natural auxin, plays important roles in many physiological responses including somatic embryogenesis, but, there is no report of the IAA metabolism in embryogenic and non-embryogenic cells. Therefore, we examined IAA metabolism in embryogenic and nonembryogenic carrot cells. In this paper the IAA metabolism in embryogenic cells and non-embryogenic cells is described. The induction of IAAsp formation was clarified in both cells. On the other hand, in non-embryogenic cells, an unknown metabolite was detected and identified as oxindole-3-acetylaspartic acid (oxIAAsp). OxIAAsp formation may be induced to eliminate excess auxin. Furthermore, endogenous IAA contents in both cells were quantified and the relationship between somatic embryogenesis and IAA metabolism is discussed.