Abstract.
The uptake of 2,4-dichlorophenoxyacetic acid (2,4-D), necessary for the in vitro induction of callus formation and somatic embryogenesis in cultured immature maize embryos, was quantified after culture on nutrient medium with [14C]2,4-D. The identity of the 14C label in the embryos was determined by high performance liquid chromatography (HPLC), and its distribution within embryos was visualized on sections of plastic embedded material. Quantification of the 14C label after a pulse label of 16 h showed a hundredfold accumulation of 2,4-D in the embryos with respect to the initial medium concentration. During tissue processing for in situ detection of 14C, however, up to 70% of the label disappeared because of the embedding process. The best structural preservation was obtained after ethanol-mediated infiltration of Technovit 7100. Water-mediated infiltration of Technovit 7100 gave the highest retention of 14C. HPLC analysis showed that more than 95% of the residual 14C label found in embryos was still 2,4-D. Autoradiography showed that the embryogenic inbred line A188 contained 14C label in distinct regions of the scutellum, coleoptile, and suspensor. The nonembryogenic inbred line A632 contained more label after 16 h of culture in a different distribution compared with A188. Subculture of the embryos for 24 and 72 h and histologic analysis showed that cell proliferation and callus formation were restricted to specific regions of the embryo in both inbred lines. The pattern of 2,4-D distribution did not codistribute with regions of proliferation, indicating that 2,4-D is not the only trigger for proliferation.
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Received August 18, 1997; accepted February 12, 1998
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Bronsema, F., van Oostveen, W., Prinsen, E. et al. Distribution of [14C] Dichlorophenoxyacetic Acid in Cultured Zygotic Embryos of Zea mays L.. J Plant Growth Regul 17, 81–88 (1998). https://doi.org/10.1007/PL00007021
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DOI: https://doi.org/10.1007/PL00007021