An Electron-Microscope Study of Germination of Conidia of Botrytis cinerea

Abstract

SUMMARY: Conidia of Botrytis cinerea have a 2-layered cell wall, a thin electron-dense outer layer and a thicker electron-transparent inner one. The cell contents comprise typical nuclei, mitochondria and endoplasm with a surrounding plasmalemma and a sparse endoplasmic reticulum. There are a few small peripheral vacuoles. On germination the outer spore wall ruptures and the emergent germ tube is surrounded by the elastic inner one and what appears to be a sheath of mucilage. A cross wall with a simple central pore is laid down at the base of the germ tube at a very early stage. As the germ tube elongates the contents of the spore flow into it, causing a large vacuole to form in the centre of the original spore. The numbers of nuclei and mitochondria suggest that divisions of these organelles take place during the early stages of germination. The mucilaginous sheath surrounding the germ tube appears to condense to give a thin electron-dense outer zone to the wall at the base of the germ tube.