DIRECT EMBRYOGENESIS FROM FEMALE HAPLOID PROTOPLASTS OF GINKGO-BILOBAL, A MEDICINAL WOODY SPECIES

Haploid protoplasts isolated from prothallus (i.e. female gametophyte) of Ginkgo biloba, at densities ranging from 5x10(4) to 10(5) protopla sts per milliliter, were able to divide and form microclones which dir ectly evolved into embryos, when they were cultured in two different l iquid media. These were : the Murashige and Tucker medium (1969) modif ied by omitting ammonium ions and supplementing with glutamine, benzyl adenine 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 16 5 to 1900 embryos ml-1 depending on the culture medium. After four mon ths, embryos at whatever stage (globular, oblong or heart) exhibited a slow growth, which delayed the transfer onto solid media.