Three-Dimensional Quantitative description of symbiont ultrastructure within the algal layer of two members of the lichen family umbilicariaceae

Abstract

The ultrastructure of the symbionts within the algal layer of Lasallia hispánica and Umbilicaria spodochroa has been investigated by applying stereological techniques to quantify cellular organelles and structures. The stereological parameters calculated were volume density (Vv) and surface density (Sv). To obtain these parameters for each cellular structure, a systematic sampling of photographic fields of the algal layer for each sample was utilized. Significant differences between the two lichen species with respect to both symbionts were observed. The cellular structures of the photobiont that differed the most between the two lichen species were the chloroplast, which differed by 15°0 in the Vv valúes and 25% in the Sv valúes, the pyrenoid (as a whole and in the diameter of pyrenoglobuli) and the mitochondria. With respect to the mycobiont, the vacuolar apparatus was of great importance in characterizing the two species, as was to a lesser extent the protoplast volume occupied by concentric bodies.