Morphological and molecular characterization of Mycorrhizal fungi associated with a disjunct stand of American chestnut (Castanea dentata) in Wisconsin

Abstract

Circa 1900 a farmer from the eastern U.S. planted eleven American chestnut (Castanea dentata) seeds on a newly established farm near West Salem in western Wisconsin. These trees were very successful, producing a large stand of over 6000 trees. Since this area was weil outside of the natural range of chestnut, these trees remained free from chestmlt blight., caused by Cryphonectria parasitica, until 1987. Because chestnut trees were almost entirely eliminated from their native range by the early 1950's, no moderm studies have examined mycorrhizae of a mature chestnut forest. To identify putative mycorrhizal associates of chestnut, our approach was two-fold: (1) an extensive fruiting body survey was conducted for 3 seasons that yielded over 400 collections, of which approximately 99 were putatively mycorrhizal, and (2) a below-ground molecular approach was used to generate DNA sequences of the ITS region from rnycorrhizae. To date, 100 root tip sequences have been generated. These sequences are phylogenetically diverse, although all are basidiomycetes or ascomycetes falling into 11 families. In addition, 84 of the 99 fruiting body collections have been sequenced. From these data a website was created, www.chestnutfingi.com, which contains a BLAST searchable database of ITS sequences coupled with pictures of both root tips and fruiting bodies.