Lacandonia granules are present in Ginkgo biloba cell nuclei

Lacandonia schismatica is a rare flowering plant with the sex organs spatially inverted. Several aspects of its cell biology are now known. Interestingly, within the cell nucleus, the chromatin is reticulated and it is associated to a novel structure named Lacandonia granules, a very abundant ribonucleoprotein particle showing similarities to perichromatin and Balbiani ring granules, which are involved in nuclear mRNA metabolism. To see whether these particles are present in other plants, we study the nucleus of Ginkgo biloba, a non-flowering plant. Light, electron and atomic force microscopy show that the cell nuclei of G. biloba are reticulated. Ultrastructural analysis showed that in the nucleoplasm, abundant intranuclear particles 32 nm in diameter are present. The EDTA regressive staining suggested that they contain RNA. Ultrastructural in situ hybridization confirmed the presence of RNA in these particles. Therefore, we conclude that the nuclei of G. biloba are reticulated and contain Lacandonia granules. We suggest that these particles may also be present in other plants.