Direct embryogenesis from female haploid protoplasts of Ginkgo biloba L., a medicinal woody species.

Haploid protoplasts isolated from prothallus (i.e. female gametophyte) of Ginkgo biloba, at densities ranging from 5×10(4) to 10(5) protoplasts per milliliter, were able to divide and form microclones which directly evolved into embryos, when they were cultured in two different liquid media. These were: the Murashige and Tucker medium (1969) modified by omitting ammonium ions and supplementing with glutamine, benzyladenine and various levels of naphthaleneacetic acid; or the Bourgin and Nitsch medium (1967) without growth regulators, supplemented with coconut milk. Three months later, the number of embryos ranged from 165 to 1900 embryos ml(-1) depending on the culture medium. After four months, embryos at whatever stage (globular, oblong or heart) exhibited a slow growth, which delayed the transfer onto solid media.