Abstract: Isolated pollen protoplasts of Nicotiana tabacum N364 K_m⁺ were fused with mesophyll protoplasts of Nicotiana rustica using PEG-high Ca/pH method. The cells resulted form fustion between immature (early-middle bicellular) pollen protoplast and mesophyll protoplast could divide to produce multicellular structures and microcalli when being cultured in a selection KM_8p,medium containing 50μg/ml kanamycin. The cells derived from fusion of mature pollen protoplast with mesophyll Protoplastant only formed tube-like structures instead of cell division. The results of the experiment indicated that the developmental stage of pollen protoplasts involved in fusion played an improtant role in deciding the developmental pathways of the fusion products:The mature pollen protoplast when fused with somatic one exhibited strong influence of gametophytic deveolpmental trends towards tube growth, whereas the younger pollen protoplast had some potential of sporophytic development which did not negatively affect division ability of its somatic partner. Regeneration and genetic characterization of plants from the microcalli are underway.

Key words: Pollen protoplast, Protoplast fusion, Protoplast culture, Nicatiana tabacum, Nicntiana rustica