Protoplasts isolated from embryogenic callus of Fortunella polyandra (Ridl.), Atalantia bilocularis (Pieree ex Guill.), Hesperethusa crenulata (Roxb.), Glycosmis pentaphylla (Retz.) Corr., Triphasia trifolia (Burm. f.) P. Wils. and Murraya koenigii (L.) Spreng. were cultured in MT (Murashige and Tucker 1969) basal medium containing 5% sucrose supplemented with 0.0, 0.001, 0.01, 0.1 or 1.0 mg l(-1) BA and 0.6 M sorbitol. The highest plating efficiencies for all species were obtained on MT basal medium containing 5% sucrose supplemented with 0.001 mg l(-1) BA. F. polyandra produced higher percentages of globular somatic embryo development, while A. bilocularis consistently showed a lower percentage of globular somatic embryo development in all 5 concentrations of BA. MT basal medium containing 5% sucrose and supplemented with 0.001 mg l(-1) BA was found to be a suitable medium for development of globular somatic embryos derived from protoplasts to form heart-shaped somatic embryos with cotyledon-like structures. The highest percentages of shoot formation for all 6 species were obtained using 0.1 mg l(-1) GA3. A complete protoplast-to-plant system was developed for F. polyandra, A. bilocularis and T. trifolia, which could facilitate the transfer of nuclear and cytoplasmic genes from these species into cultivated Citrus through protoplast fusion.

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Embryogenic callus was induced from the hypocotyl region of seedlings germinated from immature embryos of orange jessamine (Murraya paniculata (L.) Jack) on Murashige & Tucker (1969) medium containing 50 g 1-1 sucrose, 5.0 mg 1-l benzyladenine, 2.5 mg 1-1 2,4-dichlorophenoxyacetic acid and 600 mg 1-1 malt extract. Isolated protoplasts divided to produce callus on Murashige & Tucker (1969) medium containing 50 g 1-1 sucrose, 0.01 mg 1-1 gibberellin A4+7 and 600 mg 1-l malt extract. Callus developed to plantlets via somatic embryogenesis on Murashige & Tucker (1969) medium with 50 g 1 -l lactose but no plant growth regulators. These plantlets flowered in vitro on half strength Murashige & Tucker (1969) medium containing 50 g 1-l sucrose after 2 months culture.