BAMBOOZLED AGAIN - INADVERTENT ISOLATION OF FUNGAL RDNA SEQUENCES FROM BAMBOOS (POACEAE, BAMBUSOIDEAE)

Polymerase chain reaction (PCR) amplification of the nuclear internal transcribed spacer (ITS) and 5.8S regions of rDNA from woody bamboos ( Bambuseae) led 60 the recovery of fungal instead of bamboo sequences u nder a variety of PCR conditions and irrespective of whether the plant DNA was extracted from fresh leaves or silica gel-dried material. Phy logenetic analyses based on the 5.8S sequences indicated that the fung i were most likely basidiomycetes and that none was an ascomycete. A d iverse assemblage of nonascomycetous fungi was isolated from different bamboos, and various fungi coexisted in the same host plant. There wa s no evidence that closely related fungi consistently associate with c losely related host bamboos. Phylogenetic analysis based on 5.8S seque nces showed that some fungi were in lineages near Volvariella, Lentinu la, Peniophora, and Rhizoctonia, but the insufficiency of basidiomycet e and zygomycete ITS sequences in sequence data bases precluded more p recise fungal identifications. Bamboo ITS regions were amplified only when fresh leaves were surface sterilized before DNA extraction, sugge sting that the fungal associates are epiphyllous rather than endophyti c. This study highlights the possibility of inadvertent PCR amplificat ion of contaminating DNAs in molecular phylogenetic studies, particula rly when using ''universal'' amplification primers. (C) 1997 Academic Press.