Ultrastructure of spermatia and spermatium ontogeny in the rust fungus Cronartium quercuum f.sp. fusiforme

Publisher Website
Google Scholar
Abstract
Spermogonia of Cronartium quercuum f.sp. fusiforme developed just beneath the bark on galled regions of infected pine seedlings. Spermogonia consist of flattened, spreading, island-like masses of fungal tissue covered with a thin layer of liquid containing large numbers of spermatia. Spermatia arose in an annellophoric fashion from the tips of long, slender sporogenous cells produced in a distinct layer. Each sporogenous cell contained a large prominent nucleus that underwent mitosis as each spermatium initial developed. One of the resulting nuclei moved into the initial while the other remained in the sporogenous cell. Once a spermatium was delimited, it was pushed away from the tip of the sporogenous cell as another spermatium initial developed below it. Once delimited, a spermatium underwent specific morphological changes as it matured. A mature spermatium was subpyriform in shape and surrounded by a thin wall. In addition to a single large nucleus each spermatium contained ribosomes, mitochondria, lipid bodies, strands of endoplasmic reticulum, vacuole-like inclusions, and many small vesicles that packed its base. Keywords: transmission electron microscopy, pycnidia, pycnidiospores, spermogonia.