May 28, 1999

"Nobody Knows the Truffles I've Seen"
Dr. Gregory M. Mueller
Associate Curator, Mycology
Chairperson, Department of Botany
The Field Museum of Natural History

Mushrooms and false truffles don't look similar to the unaided eye; however, under the microscope, characters that suggest close evolutionary relationships can be seen. Which are better indicators, macro- or micromorphological characters? Dr. Mueller used DNA sequence data as an independent test of relationships - spore characters win.

Bio Sketch

Dr. Gregory M. Mueller received his M.S. from SIU and his Ph.D. from the University of Tennessee. Postdoctoral appointments ensued at Uppsala University, Sweden and at the University of Washington.

In addition to his museum duties, Dr. Mueller is a Lecturer, Committee on Evolutionary Biology at the University of Chicago and Adjunct Associate Professor in the Department of Biological Sciences at the University of Illinois at Chicago.

His research program centers on the systematics, ecology, and the evolution of higher fungi. One of several projects includes a survey of the mushrooms and related fungi of the Costa Rican tropical oak forests. One of this project's goals is to screen fungi for anti-AIDS and anti-cancer compounds.

Dr. Mueller is on call for the Illinois Poison Control Center and regional hospitals to help identify poisonous mushrooms.

SMSI Meeting Report of May 28, 1999.

The meeting was called to order shortly after 7PM and the first order of business was to organize who would bring what to the annual picnic to be held at York Woods South in Oak Brook on June 12. These relative trifles were followed by the featured speaker, Dr. Gregory M. Mueller, who spoke about truffles and mushrooms under the title "Nobody Knows the Truffles I've Seen", which, come to think of it, makes sense since truffles, those rugose edible fruiting bodies of European fungi, are subterranean.

With between 1 and 1.5 million the fungi are surpassed in number of species only by the beetles. The fungi lack chlorophyll and are relatively undifferentiated lower organisms which live mostly under the soil surface, although the fruiting bodies we typically associate with the name "mushroom" are notable exceptions. An SEM image of the gill mouth of a member of genus Laccaria revealed the myriad of (~15mm)spores.

The subterranean filament portion of the fungi forms an interesting symbiotic relationship (mycorrhizal) with species specific tree roots and actually promotes tree growth by increasing the area of the root, thereby increasing absorption. Spore dispersion is controlled not only by the parallel orientation of the mushroom cap to the ground, but apparently is triggered by the seasonal cycles of the host tree. Specific spore morphology can vary from genus to genus.

Dr. Mueller's work on fungi classification focuses on combining data obtained from morphological studies (no. of spores, basidium, etc.) and DNA data to build a phylogenetic tree (not mushroom) in which micromorphological characteristics seem to be good indicators of evolution. His work involves the search for answers to questions such as: Where did a particular genus originate and how did it migrate or become distributed?

Report submitted by John Macdonald, Recording Secretary