The number of nuclei in basidiospores of 63 species of ectomycorrhizal Homobasidiomycetes

Abstract

The production of even a limited number of heterokaryotic spores would be advantageous for establishing new individuals after long distance dispersal. While Suillus and Laccaria species are known to produce binucleate, heterokaryotic spores, this condition is poorly studied for most ectomycorrhizal fungi. To begin addressing this matter the number of nuclei in basidiospores was recorded from 142 sporocarps in 63 species and 20 genera of ectomycorrhizal (EM) fungi. The mean proportion of binucleate basidiospores produced by sporocarps within a species ranged from 0.00 to 1.00, with most genera within a family showing similar patterns. Basidiospores from fungi in Amanita, Cortinariaceae and Laccaria were primarily binucleate but were likely still homokaryotic. Basidiospores from fungi in Boletaceae, Cantharellus, Rhizopogonaceae, Russulaceae, Thelephorales and Tricholoma were primarily uninucleate, but binucleate basidiospores were observed in many genera and in high levels in Boletus. Further research is needed to relate basidiospore nuclear number to reproductive potential in ectomycorrhizal species.

• DAPI
• primary succession
• spore dispersal

I thank the following people for their contribution to this work. Dan Segotta facilitated the work at the Oregon Dunes National Recreation Area. Sara Ashkannejhad and Kevin Hood were the primary field assistants. Joe Ammirati, Mike Castellano, Efrén Cázares, Dan Luoma, Brandon Methany, Thom O’Dell, Michelle Seidl and Kris Shanks provided taxonomic expertise. Linda Ciuffetti and Pat Martinez provided assistance in DAPI staining. Linda Ciuffetti and Joey Spatafora provided access to their fluorescence microscope. Randy Molina and the Mycology Team provided a wide variety of advice and support. Finally I thank David Hibbett and two anonymous reviewers for helpful comments on the manuscript. This work was financed by the NRI Competitive Grants Program/USDA award 99-35107-7843 and through support by the US Forest Service PNW Research Station.