histological changes of carrot (daucus carota l.) petiole somatic embryogenesis in some media

abstract somatic embryogenesis is a new approach to in vitro plant propagation. this technique is based on stem cell obtain and its differentiation to a complete plant. this is affected by components of media culture. so, the effects of ms, b5 and nl media on carrot petiole somatic embryogenesis investigated via histological experiment. to do this, carrot petioles (with 1 cm dimension) cultured in liquid phase of these media. different concentrations of iaa and 2,4-d were used for induction of somatic embryogenesis. for histological study, after induction phase, sampling from cultured petioles was done and fixed in faa solution. after dehydration, paraffin embedding, blocking, sectioning and staining, samples were used to examine the specimen for the documentation. results indicated that there is significant differences among ms, b5 and nl media with respect to carrot somatic embryogenesis (p<0.01). the highest and the lowest number of embryos were counted in b5 and ms, respectively. in b5 supplemented with 0.904 µm 2,4-d, the highest number of embryos were obtained (p<0.01). histological studies of carrot petiole showed the small cells with dense cytoplasm in b5 and the large nuclei with many starch grains in nl which are symptoms of embryonic cells. as well, no differentiated pme cells were observed in sub epidermis of petiole in ms.