An immunofluorescence study on calmodulin distribution during somatic and zygotic embryogenesis of carrot (Daucus carota L.)

The distribution of calmodulin was studied during somatic and zygotic embryogenesis and during germination of carrot. Calmodulin levels were visualized by immunofluorescence, using semi-thin sections of different developmental stages of embryogenesis. In proembryogenic masses the distribution of calmodulin was highly variable between individual cells. In later stages of somatic embryogenesis, calmodulin was mainly found associated with organelles in the protoderm. In contrast, in zygotic embryos calmodulin was found to be evenly distributed over the entire embryo. A polarized distribution of calmodulin was observed during germination of the zygotic embryos. Calmodulin was mainly found in the cytoplasm of the epidermis of the cotyledons and the hypocotyl, but was clearly associated with organelles in the root side of the germling. It is concluded that the distribution of calmodulin differs in somatic and zygotic embryos of carrot and that the distribution in somatic embryos resembles the distribution in germinating zygotic embryos.