Morphometric and Cytochemical Ultrastructural Analyses of the Gunnera kaalensis/Nostoc Symbiosis

Abstract

Quantitative and cytochemical analyses on Gunnera kaalensis stem nodules, which contained the cyanobacterium Nostoc, show that many of the Nostoc cells are degenerate and surrounded by layers of material similar in density to Gunnera cell walls and middle lamellae, which appear swollen. The surrounding encapsulating material is formed early in the infection process and remains consistent in thickness. Gunnera cells appear, for the most part, highly vacuolated, and acid phosphatase can be localized at various sites, depending on the age of the tissue sampled.