Structure and function of the tentpole in the reproductive process of Ginkgo biloba L.

The tentpole is a unique structure of the female gametophyte in Ginkgo biloba; however, its exact functions in the reproductive process are unclear. In the present study, we used semi-thin sectioning and electron microscopy to study the structure and function of the tentpole during fertilization in G. biloba. The tentpole was always initiated between two or more deeply immersed archegonia. Before fertilization, the tentpole had developed into a column-like structure, protruding toward the archegonial chamber; cells at the periphery of tentpole were loosely ranged, and abundant lipid droplets and starch grains were accumulated in the tentpole cells. After fertilization, the tentpole degenerated, and some membranous debris was overlaid on its surface. In addition, there were significant decreases in the lipids and starch grains. These results suggested that the tentpole led to the degeneration of the megaspore membrane and then supported the pliable apex of the nucellar tissues. Importantly, the tentpole also contributed to supplying nutrition for fertilization and embryo development.