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To clarify the molecular biological aspects occurring during the induction of somatic embryogenesis, the stress-induced changes in protein pattern and the proteins associated with somatic embryogenesis induced by stress in carrot (Daucus carota L.) were investigated. In two dimensional polyacrylamide gel electrophoresis (2D-PAGE), 6 spots with molecular weight of 63-65 kilo Dalton (KDa) showing pI ranging from 6.0-6.5, and 2 spots of molecular weight 45 KDa with a pI of 5.0 were detected in the extracts of apical tip segments treated with cadmium chloride, sucrose and sodium chloride. Three spots out of the 6 spots of 63-65 KDa molecular weight and the two 45 KDa spots were also detected in the extracts of 2,4-dichlorophenoxy acetic acid (2,4-D) -induced embryogenic cells, but not in those of non-embryogenic cells. Furthermore, these 5 spots were also detected in the extracts of hypocotyl segments cultured with 2,4-D for more than 4weeks. Judging from the relationship between accumulation of these proteins and acquisition of embryogenic competence, these proteins may be related to acquisition and/or maintenance of embryogenic competence.

Abstract. An action spectrum was determined for lightinduced formation of adventitious shoots in hairy roots of horseradish (Armoracia rusticana Gaert., Mey. et Scherb.) cultured in vitro. Near ultraviolet (350-400 nm), blue (440-460 nm) and red light (600-680 nm) were most effective in inducing formation of adventitious buds. Farred light (730 nm) inhibited the promotive effect of all three wavelength regions. These results are consistent with induction by phytochrome(s) of adventitious shoots in hairy roots of horseradish.

To clarify that the presence of Ri T-DNA genes are not prerequisite for the light-induced bud formation in horseradish (Armoracia rusticana) hairy roots, leaf and root segments of nontransformed horseradish plants were used as explants. Bud formation from nontransformed tissues was observed in hormone-free medium under 16 h daylight conditions, but not under continuous darkness. To investigate the effects of growth regulators on bud formation, leaf and root explants were treated with auxin (1-naphthaleneacetic acid; NAA) and / or cytokinin (6-benzyl-aminopurine; BA). The most effective treatment in the dark to stimulate bud formation was BA at 1 mg·1(-1). These results show that adventitious bud formation in horseradish can be induced by light and growth regulators, and especially cytokinin, may be involved in bud formation, irrespective of whether the tissues were transformed with Ri T-DNA.

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