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Title: PESTALOTIOPSIS MACULANS IS A PARASYMBIONTIC FUNGUS IN NORTH AMERICAN LICHENS

Author
item SUN, HENRY - FLORIDA STATE UNIV.
item DEPRIEST, PAULA - SMITHSONIAN INST.
item GARGAS, ANDREA - SMITHSONIAN INST.
item Rossman, Amy
item FRIEDMAN, IMRE - FLORIDA STATE UNIV.

Submitted to: Symbiosis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2002
Publication Date: 3/3/2003
Citation: Sun, H.J., Depriest, P.T., Gargas, A., Rossman, A.Y., Friedman, I. 2003.Pestalotiopsis maculans is a parasymbiontic fungus in North American lichens. Symbiosis 33(2):215-226.

Interpretive Summary: Lichens are a group of fungi that occur throughout the world in an association with one or more alga. Together these organisms can survive in environments where neither organism could exist alone. Lichens are important indicators of air quality and of specific ecological habitats. In addition they produce interesting and unusual metabolites that are used for medicinal and agricultural purposes. In this study it was discovered that a second extra fungus was associated with many lichens in North America. Because it is not the primary fungal associate, it is called a parasymbiont. The same second fungus was found in most of the lichens that were examined from North America thus it is considered the dominant extra fungus. Lichens outside of North American did not have this extra fungus. This research will be used to determine why lichens can survive in diverse, often extreme habitats.

Technical Abstract: By culturing small thallus portions in nutrient medium, it could be shown that Pestalotiopisis maculans (Corda) Nag Raj is a dominant parasymbiontic fungus in North American lichens. P. maculans was present in all twelve lichen specimens (10 Cladina, 1 Usnea, and 1 Parmetroma) collected in the eastern parts of North America between Ontario, Canada and Oaxaca, Mexico. In each lichen the dominant parasymbiont was present throughout the thallus. Cultures of different tissue samples excised from the thallus of Cladina indicate that P. maculans is confined to the metabolically active outer medulla, but is not in direct contact with the photobiont cells. When growing in pure culture, P. maculans and the mycobiont Cladina subtenuis show different hyphal morphologies in the environmental scanning electron microscope, but these characteristics are not present within the lichen thallus. Twenty-one lichen species collected in Germany, the Canary Islands, New Zealand, and Israel contained a variety of secondary fungi (but not Pestalotiopsis) with varied abundance and narrower geographic distribution.