Stayin’ alive: survival of mycorrhizal fungal propagules from 6-yr-old forest soil Nhu H. NGUYEN a, *, Nicole A. HYNSON b , Thomas D. BRUNS a a Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA b Department of Botany, University of Hawaii Manoa, Honolulu, HI, USA article info Article history: Received 23 December 2011 Revision received 27 April 2012 Accepted 14 May 2012 Available online - Corresponding editor: Kabir G. Peay Keywords: Dormancy Ectomycorrhizal fungi Longevity Spore bank Symbiosis abstract Spores and sclerotia are the main propagules that allow fungi to persist through unfa- vorable conditions and disperse into new environments. Despite their importance, very little is known about their longevity and dormancy, especially in ectomycorrhizal fungi. To assess the viability of ectomycorrhizal fungal spores in forest soil, we collected and buried non-sterile forest soil, in pots, in the field distant from an inoculum source. After 6 yr, a subset of this soil was assayed for viable spores by baiting the fungi with Bishop pine (Pinus muricata) seedlings. Our results show that the three most frequent colonizers in year 1 continued to colonize significant percentages of seedlings in year 6: Wilcoxina mikolae (77 %), Rhizopogon vulgaris (13 %) and Suillus brevipes (9 %). While three species that colo- nized low percentages of seedlings in year 1, Suillus pungens (1 %), Rhizopogon salebrosus (2 %), and Thelephora terrestris (5 %) were not recovered in year 6. Laccaria proxima, a species not seen in year 1, was recovered on a single seedling in year 6. This is the first report of long-term survival of S. brevipes and W. mikolae. Our results reveal a more complete picture of ectomycorrhizal fungal spore longevity in soil spore banks. ª 2012 Elsevier Ltd and The British Mycological Society. All rights reserved. Introduction Propagules such as spores and sclerotia are a means for fungi to escape their current environment, overcome dispersal barriers, and establish in a new favorable habitat. Dispersal may involve these propagules being carried by the air or through the guts of various animals (Claridge et al. 1992; Lilleskov & Bruns 2005). Aerial dispersal may involve the risk of spore dehydration (Ashkannejhad & Horton 2006) or UV damage (Ulevicius et al. 2004) that can lead to a loss of viability. Even if the spores are able to survive these barriers, reaching new substrata does not guarantee favorable conditions for germination, particularly in ectomycorrhizal fungi (Massicotte et al. 1994; Rusca et al. 2006). To counter this problem, it was suggested that some fungi produce resistant propagules that can form a spore bank and potentially wait for decades before germination (Miller et al. 1994; Bruns et al. 2009). Most reports of spore banks are based on anecdotal evidence (Putnam & Sindermann 1994) and few experiments have attempted to address the question of spore survival through an extended time (Bruns et al. 2009; Nara 2009). This is especially true for ectomycorrhizal fungi (EMF). Longevity and dormancy of EMF spores have been studied using various microscopy techniques (Lamb & Richards 1974; Miller et al. 1993, 1994; Torres & Honrubia 1994) and host seedling bioassays (Castellano & Molina 1989; Ashkannejhad & Horton 2006; Ishida et al. 2008; Bruns et al. 2009). Some EMF spores remained viable from 1 month and up to 4 yr in various storage conditions. Bruns et al. (2009) showed that spores of several Rhizopogon species remained viable for at * Corresponding author. Tel.: þ1 510 643 5483; fax: þ1 510 642 4995. E-mail address: xerantheum@berkeley.edu (N.H. Nguyen). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/funeco 1754-5048/$ e see front matter ª 2012 Elsevier Ltd and The British Mycological Society. All rights reserved. http://dx.doi.org/10.1016/j.funeco.2012.05.006 fungal ecology xxx (2012) 1 e6 Please cite this article in press as: Nguyen NH, et al., Stayin’ alive: survival of mycorrhizal fungal propagules from 6-yr-old forest soil, Fungal Ecology (2012), http://dx.doi.org/10.1016/j.funeco.2012.05.006