Embryogenesis from microspores of Ginkgo biloba L., a medicinal woody species.

The present work establishes that isolated microspores of Ginkgo biloba L. cultured at densities of 1.5 to 5·10(4) per milliliter in Bourgin and Nitsch (1967) liquid medium are able to divide, both in the presence and in the absence of exogenous growth regulators, and to germinate by growing a pollen tube. In all experiments the microspores exhibited various modes of division leading to embryo formation in the liquid medium. Four weeks later, the microspores which had been previously submitted to various electrical stresses showed pro-embryo development earlier than those which had not. After ten weeks the number of embryos was found to be 300 to 5300 ml(-1) following the experiments. When the embryos exhibited a slower growth in liquid medium, they were transferred onto various solid media for maturation. Two months later, embryos had proliferated visibly.