Ultrastructure of conidium germination of Cochliobolus carbonus

Abstract

Multiseptate conidia of Cochliobolus carbonus germinate in water by one or two polar germ tubes. The septa between cells within a conidium contain a central pore, which is plugged before germination but open during germination, so that all cells are interconnected. During germination, vacuoles enlarge, endoplasmic reticulum profiles increase in number, and mitochondria change from a spherical form with loosely arranged cristae to an elongated form with closely packed cristae. The conidium wall consists of an inner electron-translucent layer and an outer electron-opaque layer. The germ tube wall is continuous with the innermost layer of the conidium wall. Shortly after germination, a septum with a central pore forms in the germ tube by invagination where it emerges from the conidium. The germ tube wall is surrounded by a fibrillar sheath. The presence of apical vesicles in the germ tube tip is confirmed. The associations of Woronin bodies with septal pores and microbodies, of lipids with vacuoles, and of microbodies with lipids and vacuoles are discussed.

An electron microscopical study of the development of peroxisomes during formation and germination of ascospores in the methylotrophic yeast Hansenula polymorpha

“…In filamentous fungi observations have been made which indicate a significant role ofperoxisomes during the sporulation process (Cole, 1973;Hess and Weber, 1974). In addition,.these organelles may have a possible function during germination of spores (Powell, 1976;Murray and Maxwell, 1974;Chong and Barr, 1973), similar to the function of peroxisomes in developing seeds (Hutton and Stumpf, 1969;Tolbert, 1971;Gerhardt, 1973).…”

The Fine Structure of Germinating Resting Spores of Olpidium brassicae.

“…The presence of numerous membrane-bound vesicles concentrated at the site of the breakdown of the Olpidium resting spore wall suggests its involvement in the process leading to the formation of an exit tube. Similar vesicles have been observed in the germinating zoosporangia of 0. brassicae (Temmink, 1971) and of Polymyxa betae (D'Ambra and Mutto, 1977), in the penetration structure of several fungi (Sargent et al, 1973;McKeen, 1974), in spore germination (Murray and Maxwell, 1974;Hemmes and Wong, 1975) and in hyphal elongation (Grove and Bracker, 1970;Beckett et al, 1974). Thus, they seem to occur widely both in wall dissolution and its synthesis.…”