Cytoplasmic dynamics of the tubulin and actin cytoskeletons during teliospore germination and basidiospore formation in a rust fungus

Abstract

Gymnosporangium clavipes C. & P. is a basidiomycetous fungus belonging to a common and destructive group of plant pathogens known to as the rusts. The rusts are best known for their damage to economically important crops including corn, wheat, oats, and barley and have become important model organisms in cell biology studies. Of all the stages in their complex life cycle, perhaps the most interesting are those involved in teliospore germination and basidiospore formation.As illustrated with scanning electron microscopy teliospores of G. clavipes are ellipsoidal spores consisting of an apical and basal cell (Fig. 1). Upon germination of the teliospore, four discrete morphological events occur that give rise to mature basidiospores. These events include: i) emergence of germ tubes (Fig. 2), ii) formation of three septal cross walls segmenting the germ tube into four compartments (Fig. 3), iii) growth of a single sterigma from each compartment, (Fig. 4) and iv) enlargement of sterigmal tips to form individual basidiospores (Fig. 5). The objective of this research was to determine whether these developmental stages were temporally correlated with changes in the organization of the tubulin and actin cytoskeletons.