Selectivity of photobiont choice in a defined lichen community: inferences from cultural and molecular studies

Abstract

 Axenic cultures of lichen photobionts isolated from bark-inhabiting lichen thalli of the Physcietum adscendentisOchsner were identified by light microscopy and sequence comparisons of internal transcribed spacer rDNAs to investigate principles of lichenization within a defined lichen sociological unit. The photobiont identity of eight lichen species is reported for the first time (photobiont species in square brackets) : Lecania cyrtella (Ach. . The observation that pioneer lichens without vegetative propagules, growing on smooth bark, had Trebouxia arboricola as photobiont can be explained by the assumption of a free-living population of Trebouxia arboricola. Species of photobionts from Xanthoria parietina were morphologically and genetically different from those of Physcia adscendens and Phaeophyscia orbicularis, respectively ; a finding that does not support the previous assumption that Xanthoria parietina takes over its algal partner from a Physcia species, at least at the sites investigated.)

The Distribution of Group I Introns in Lichen Algae Suggests That Lichenization Facilitates Intron Lateral Transfer

“…The PCR primers were NS7M and LR1850 and the reaction conditions were as in Friedl and Zeltner (1994). PCR products were directly sequenced using the dideoxy sequencing method (Sanger et al, 1977) with the oligonucleotide primers described in Beck et al (1998). Fluorescent-labeled primers were used in sequencing reactions with Licor L4000 and ALFexpress automated sequencers.…”

Revisiting photobiont diversity in the lichen family Verrucariaceae (Ascomycota)

“…These extracts however contain all organisms co-existing with the principal symbionts, such as algae growing on the lichen thallus surface or in cracks or cavities within the lichen (accessory algae), and it may therefore be difficult to distinguish the main symbiotic algal component of a lichen thallus from opportunistic cohabitants (Helms et al, 2001;Honegger, 2009). These risks can be minimized if symbiotic algae are isolated from the thallus and DNA extracts prepared from unialgal photobiont cultures (Beck & Koop, 2001;Beck et al, 1998Beck et al, , 2002.…”

Eisosome Ultrastructure and Evolution in Fungi, Microalgae, and Lichens

“…Lichens, which are named for their ϳ20,000 different fungal (mycobiont) species, harbor trebouxiophyte microalgae (photobionts) in just two genera: Trebouxia (56) and Asterochloris (57). Our survey includes Trebouxia jamesii from the Candelaria concolor lichen (58) and Asterochloris sp. from the Cladonia grayi lichen (47).…”