Ultrastructural Effects of Peroxyacetyl Nitrate (PAN) on Two Lichen Species

Abstract

Samples of Hypogymnia enteromorpha (Ach.) Nyl. and Parmelia sulcata Tayl. were fumigated with peroxyacetyl nitrate (PAN) for 28 hours in seven days at 100 ppb and 32 hours in eight days at 50 ppb. Photosynthesis rates decreased in both species, with more decrease in P. sulcata than in H. enteromorpha. Analysis of transmission electronmicrographs revealed abnormally high accumulation of starch in the chloroplasts of both lichen species and slight decreases in amount of pyrenoid area. Anticipated significant deterioration and disappearance of thylakoid membranes did not occur.