Use of DNA sequencing to detect pathogenic, saprotrophic, and stain fungi in sapwood of declining red pine (Pinus resinosa) in the Upper Midwest
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In: Browning, John; Palacios, Patsy, comps. Proceedings of the Western International Forest Disease Work Conference; 2012 Oct. 8-12; Lake Tahoe, CA. [Place of publication unknown]: Western International Forest Disease Work Conference: 101-110.
An inexpensive kit was developed to collect wood samples for molecular detection of pathogenic, saprotrophic and stain fungi in declining Pinus resinosa in the Upper Midwest. The kit contained materials for "clean" collection of sapwood drill shavings, which were then subjected to PCR of the rDNA ITS region with fungal-specific primers, followed by cloning and sequencing. Twenty-seven stands with declining P. resinosa lacking obvious fungal fruiting bodies were sampled by natural resources personnel throughout MN, WI, and MI. No single mortality agent predominated and causal agent(s) likely differed by location. A complex interaction of abiotic and biotic agents is likely involved in the symptomatic stands. None of the selected trees tested positive for Heterobasidion irregulare with either a pathogen-specific primer or more general ITS primers. Root rot fungi that were detected in the declining and dead trees included Armillaria solidipes (= A. ostoyae), Scytinostroma sp., and two species of Leptographium, the genus associated with Red Pine Pocket Mortality. The brown rot fungi Coniophora arida and C. puteana, known to cause root and butt rots in conifers in the western U.S., were found on both living, declining trees and dead snags. Many ophiostomoid sapstain fungi were present and were usually associated with signs of insect activity. Saprotrophic decay fungi were prevalent with white rot fungi predominating, including Amylostereum chailletii, Hyphoderma setigerum, Hypholoma fasiculare, and Trichaptum fuscoviolaceum. Numerous ascomycetes, including endophytic fungi and yeasts, were recovered in great quantities; many of these were uncommon and site specific. Thirty-two unique sequences from basidiomycetes and 129 from ascomycetes had no species, genus, or family identification in GenBank, illustrating the complex and largely unstudied community of fungi found in declining P. resinosa. The procedures presented here can be used to address questions of fungal diversity and ecology as well as forest pathology, and the technique can be easily adapted to screening with species specific primers when screening for individual pathogens, thus reducing cost and labor.
KeywordsHeterobasidion irregulare; Armillaria Root Rot; Red Pine Pocket Mortality; ITS (internal transcribed spacer); root rot fungi; white rot fungi; brown rot fungi; sapstain; Pinus resinosa
Banik, M.T.; Lindner, D.L.; Juzwik, J.; Glaeser, J.A. 2013. Use of DNA sequencing to detect pathogenic, saprotrophic, and stain fungi in sapwood of declining red pine (Pinus resinosa) in the Upper Midwest. In: Browning, John; Palacios, Patsy, comps. Proceedings of the Western International Forest Disease Work Conference; 2012 Oct. 8-12; Lake Tahoe, CA. [Place of publication unknown]: Western International Forest Disease Work Conference: 101-110.