High cyanobiont selectivity of epiphytic lichens in old growth boreal forest of Finland

Abstract

Research Summary• Here, cyanobiont selectivity of epiphytic lichen species was examined in an old growth forest area in Finland.• Samples of the eight lichen species were collected from the same aspen ( Populus tremula ) and adjacent aspens in the same stand. The cyanobionts of these samples were compared with free and symbiotic Nostoc obtained from other habitats and geographic regions.• Our results, based on the phylogenetic analysis of a partial small subunit of the ribosomal DNA (16S rDNA) and the rbcLX gene complex did not show any correlation with the geographic origin of the samples at any spatial scale. Instead, there was a correlation between the cyanobionts and the alleged taxonomy of their mycobionts.• The results indicate that the lichen species examined are highly selective towards their cyanobiont partners. Only Lobaria pulmonaria proved to be more flexible, being able to associate with a wide range of Nostoc . A same Nostoc strain was found to form associations with taxonomically unrelated lichens indicating that the cyanobiontmycobiont associations as a whole were not highly specific in the examined species.

Cyanobacteria produce a high variety of hepatotoxic peptides in lichen symbiosis

“…strain 152. The lichen-symbiotic Nostoc form several lineages, including those associated with host fungi of the Nephroma guild (A-F) and the Peltigera guild (G-L) (4,12). This shows that the geographical origin of a lichen specimen does not predict the identity of the Nostoc symbiont, and that the production of detectable amounts of toxins is not restricted to well-defined groups within Nostoc.…”

Fungal-algal interactions inRamalina menziesiiand its associated epiphytic lichen community

“…Some fungi show high selectivity, and they associate with a particular photobiont phylogenetic clade or species (Kroken & Taylor 2000;Helms et al 2001;Beck et al 2002;PierceyNormore 2004PierceyNormore , 2006Yahr et al 2004;Stenroos et al 2006;Myllys et al 2007). Other fungal species are far less selective towards their photobiont partners (Wirtz et al 2003;Piercey-Normore 2004;Yahr et al 2004;Myllys et al 2007); some may occasionally or always associate with two photobiont species (Piercey-Normore 2006; Casano et al 2011). Some fungal species are able to partner up with photobionts belonging to different kingdoms, and which photobiont partner gets involved in the symbiosis may depend on environmental conditions (Goffinet & Bayer 1997;Tønsberg & Goward 2001;Summerfield et al 2002).…”

New morphological aspects of cephalodium formation in the lichenLobaria pulmonaria(Lecanorales, Ascomycota)

“…However, Lobaria pulmonaria and Peltigera venosa are exceptions to this rule. Both species were shown to associate with a wide range of Nostoc strains (Paulsrud & Lindblad 2002;Rikkinen et al 2002;Myllys et al 2007). …”

“…Lichen-forming fungi seem to be highly selective in choosing their cyanobacterial partner because only a few closely related Nostoc strains typically serve as the appropriate symbiotic partner for each fungal species (Paulsrud et al 1998(Paulsrud et al , 2000Lohtander et al 2003;Stenroos et al 2006;Myllys et al 2007;Lü cking et al 2009;Rikkinen 2009). However, Lobaria pulmonaria and Peltigera venosa are exceptions to this rule.…”