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Calli were induced from the crown of seedlings or lateral bud of young spears of Asparagus officinalis L. on Linsmaier and Skoog's (LS) solid-medium supplemented with 5 μ M 2,4-dichlorophenoxyacetic acid (2,4-D). Embryogenic callus was selected from induced calli and proliferated in LS liquid medium supplemented with 5 μ M 2,4-D. Non-vitrified somatic embryos were formed and efficiently developed into club-shaped embryos in LS hormone-free medium with 1 % gelrite in a culture vessel capped with an aseptic ventilative filter. Non-vitrified club-shaped embryos developed into normal plants when transferred to half-strength LS medium without hormones, and 0.8 % agar. Carbon dioxide concentration and moisture content inside the culture vessels were measured, and their effect on embryo development is discussed.

Root explants of Eustoma grandiflorum were bombarded with plasmid pBI221 harboring the uidA gene encoding 9-glucuronidase (GUS) driven by a cauliflower mosaic virus 35 S promoter, and the effects of pre-and post-bombardment culture in various starvation media on the number of blue spots of GUS-expressing cells were studied. It was found that pre-and post-bombardment culture in nitrogen-depleted media increased the expression frequency of the transgene, by 4-to 8-times that of the control, and that 3-h pre-culture in the nitrogen-depleted medium gave the highest expression frequency.