Somatic embryogenesis in Clematis integrifolia x C-viticella

Nodal sections of Clematis integrifolia x C. viticella were cultured at 24 degreesC in darkness on a medium containing the salts and vitamins of Murashige and Skoog (1962) supplemented with sucrose (30 g l(-1)), 2 muM 6- benzylaminopurine (BAP) and 0.5 muM 4-indole-3-yl-butyric acid (IBA). These explants produced a white friable callus on their surfaces. Somatic embryos were first observed on the surface of the callus after eighteen months in culture. Thereafter, pieces (125 mm(3)) of the embryogenic mass were subcultured every 4 weeks and continued to produce somatic embryos over the two-year period of observation. A mean (+/- SE) of 64 +/-4 cotyledonary stage embryos were observed per 125 mm(3) callus four weeks after transfer to fresh medium. Comparison of the effect of growth regulators on conversion showed that the highest frequency of unipolar and bipolar conversions occurred on medium containing 10 muM kinetin and 1 muM BAP. Shoots were excised from embryos and inserted in Sorbarods saturated with liquid medium containing 0.05 muM IBA and 0.05 muM 1-naphthalenacetic acid. After four weeks 88% had formed root and survived transfer to compost in a greenhouse.