Distribution of Fluorescence Emitted by Acridine Orange during Somatic Embryogenesis of Carrot (Daucus carota L.)

Abstract

Acridine orange was used as a fluorescent probe for nucleic acids to investigate the establishment of polarity during somatic embryogenesis of carrot (Daucus carota L.) . The fluorescence emitted by acridine orange in cell clusters and somatic embryos was observed using a confocal laser scanning microscope. The fluorescence was split into a green component and a red component by optical filters. The green fluorescence emitted by acridine orange, which intercalated into double-stranded nucleic acids, was observed mainly in the nucleus. An increase in intensity of the red fluorescence emitted by acridine orange, which bound to single-stranded nucleic acids, was observed after the somatic embryo induction treatment without 2, 4-D in the medium. In addition, the biased distribution of the red fluorescence was observed in cell clusters before the formation of globular embryos. The biased distribution of fluorescence suggested that there were physiologically different cells in these cell clusters and supported the notion that physiological polarity appeared prior to the formation of globular embryos.