Abstract: A new method combining enzymatic maceration with osmotic shock was developed for isolation of living embryo sac and its protoplasts in Nicotiana tabacum L. The principle of this method was that the ovules submitted to enzymatic treatment and osmotic shock could release embryo sacs along with some internal ovular cells through either the funicle cut end or the micropyle. Factors affecting embryo sac isolation were investigated, including concentration of mannitol as a shock osmoticum and in enzymesolution ,duration of enzymatic maceration,and duration of osmotic shock. As a result a procedure was established: Ovules at mature embryo sac stage were macerated for 2. S h in 1 %–1.5% cellulase R-10 and 0. 5% macerozyme R-10 (or 1% Pectinase,Serva) dissolved in 13% mannitol solution using microshaker,followed by osmotic shock for 15–30 min with enzyme free 8% mannitol solution and gentle agitation using a pipette. Using a capillary,50–70 embryo sacs could be collected manually in one hour. The embryo sacs thus isolated could be kept viable from which protoplasts of egg cell and other componcnt cells could be further isolated. An additional interesting phenomenon was that osmotic shock often caused in situ fusion the protoplasts of egg cell and synergids. The rate of fusion ranging 9%—71.9% could be controlled by modification of the procedure. This phenomenon merits further attention both from basic and practical point of view. The present method gives the advantages of faciliting isolation and promoting good harvest of viable embryo sacs/female protoplasts within a relative short time.

Key words: Embryo sac isolation, Egg cell isolation, Female cell fusion, Nicotiana Tabacum