Scanning electron microscopy of the sporosorus in Polymyxa betae (Plasmodiophoromycetes)

Abstract

Results are reported for observations of sporosori of Polymyxa betae Keskin made with the scanning electron microscope on sugar-beet roots. Sporosori were extracted from the host cells 15, 20, and 30 days after inoculation, purified, and observed with the scanning electron microscope. The morphology of sporosori differs, depending on their stage of maturation. Immature resting spores (cysts) are polyhedral and characterized by a wall rich in folds that converge towards the upper portion in six ridges arranged regularly in a spoke fashion. During maturation the walls of the individual resting spores unfold and come into direct contact with each other. Towards the end of maturation the resting spores become rounded and, after their walls split, germination takes place. After germination the sporosori still conserve their structure as a result of the effect of a cementing substance that keeps the walls united. Details are given of the system used to extract and purify the sporosori for observation using the scanning electron microscope.