TY - JOUR
T1 - Determining threshold values for barcoding fungi
T2 - lessons from Cortinarius (Basidiomycota), a highly diverse and widespread ectomycorrhizal genus
AU - Garnica, Sigisfredo
AU - Schön, Max Emil
AU - Abarenkov, Kessy
AU - Riess, Kai
AU - Liimatainen, Kare
AU - Niskanen, Tuula
AU - Dima, Bálint
AU - Soop, Karl
AU - Frøslev, Tobias Guldberg
AU - Jeppesen, Thomas Stjernegaard
AU - Peintner, Ursula
AU - Kuhnert-Finkernagel, Regina
AU - Brandrud, Tor Erik
AU - Saar, Günter
AU - Oertel, Bernhard
AU - Ammirati, Joseph F.
PY - 2016/4
Y1 - 2016/4
N2 - Different distance-based threshold selection approaches were used to assess and compare use of the internal transcribed spacer (ITS) region to distinguish among 901 Cortinarius species represented by > 3000 collections. Sources of error associated with genetic markers and selection approaches were explored and evaluated using MOTUs from genus and lineage based-alignments. Our study indicates that 1%-2% more species can be distinguished by using the full-length ITS barcode as compared to either the ITS1 or ITS2 regions alone. Optimal threshold values for different picking approaches and genetic marker lengths inferred from a subset of species containing major lineages ranged from 97.0% to 99.5% sequence similarity using clustering optimization and UNITE SH, and from 1% to 2% sequence dissimilarity with CROP. Errors for the optimal cutoff ranged from 0% to 70%, and these can be reduced to a maximum of 22% when excluding species lacking a barcode gap. A threshold value of 99% is suitable for distinguishing species in the majority of lineages in the genus using the entire ITS region but only 90% of the species could be identified using just the ITS1 or ITS2 region. Prior identification of species, lacking barcode gaps and their subsequent separate analyses, maximized the accuracy of threshold approaches.
AB - Different distance-based threshold selection approaches were used to assess and compare use of the internal transcribed spacer (ITS) region to distinguish among 901 Cortinarius species represented by > 3000 collections. Sources of error associated with genetic markers and selection approaches were explored and evaluated using MOTUs from genus and lineage based-alignments. Our study indicates that 1%-2% more species can be distinguished by using the full-length ITS barcode as compared to either the ITS1 or ITS2 regions alone. Optimal threshold values for different picking approaches and genetic marker lengths inferred from a subset of species containing major lineages ranged from 97.0% to 99.5% sequence similarity using clustering optimization and UNITE SH, and from 1% to 2% sequence dissimilarity with CROP. Errors for the optimal cutoff ranged from 0% to 70%, and these can be reduced to a maximum of 22% when excluding species lacking a barcode gap. A threshold value of 99% is suitable for distinguishing species in the majority of lineages in the genus using the entire ITS region but only 90% of the species could be identified using just the ITS1 or ITS2 region. Prior identification of species, lacking barcode gaps and their subsequent separate analyses, maximized the accuracy of threshold approaches.
U2 - 10.1093/femsec/fiw045
DO - 10.1093/femsec/fiw045
M3 - Journal article
C2 - 26929438
SN - 0168-6496
VL - 92
JO - F E M S Microbiology Ecology
JF - F E M S Microbiology Ecology
IS - 4
M1 - fiw045
ER -