Green-Algal Photobiont Diversity (Trebouxia Spp.) in Representatives of Teloschistaceae (Lecanoromycetes, Lichen-Forming Ascomycetes)
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Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2014 Green-algal photobiont diversity (Trebouxia spp.) in representatives of Teloschistaceae (Lecanoromycetes, lichen-forming ascomycetes) Nyati, Shyam ; Scherrer, Sandra ; Werth, Silke ; Honegger, Rosmarie Abstract: The green algal photobionts of 12 Xanthoria, seven Xanthomendoza, two Teloschistes species and Josefpoeltia parva (all Teloschistaceae) were analyzed. Xanthoria parietina was sampled on four continents. More than 300 photobiont isolates were brought into sterile culture. The nuclear ribosomal internal transcribed spacer region (nrITS; 101 sequences) and the large subunit of the RuBiSco gene (rbcL; 54 sequences) of either whole lichen DNA or photobiont isolates were phylogenetically analyzed. ITS and rbcL phylogenies were congruent, although some subclades had low bootstrap support. Trebouxia arbori- cola, T. decolorans and closely related, unnamed Trebouxia species, all belonging to clade A, were found as photobionts of Xanthoria species. Xanthomendoza species associated with either T. decolorans (clade A), T. impressa, T. gelatinosa (clade I) or with an unnamed Trebouxia species. Trebouxia gelatinosa genotypes (clade I) were the photobionts of Teloschistes chrysophthalmus, T. hosseusianus and Josefpoel- tia parva. Only weak correlations between distribution patterns of algal genotypes and environmental conditions or geographical location were observed. DOI: https://doi.org/10.1017/S0024282913000819 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-107425 Journal Article Published Version Originally published at: Nyati, Shyam; Scherrer, Sandra; Werth, Silke; Honegger, Rosmarie (2014). Green-algal photobiont diversity (Trebouxia spp.) in representatives of Teloschistaceae (Lecanoromycetes, lichen-forming as- comycetes). The Lichenologist, 46(02):189-212. DOI: https://doi.org/10.1017/S0024282913000819 The Lichenologist 46(2): 189–212 (2014) 6 British Lichen Society, 2014 doi:10.1017/S0024282913000819 Green-algal photobiont diversity (Trebouxia spp.) in representatives of Teloschistaceae (Lecanoromycetes, lichen-forming ascomycetes) Shyam NYATI, Sandra SCHERRER, Silke WERTH and Rosmarie HONEGGER Abstract: The green algal photobionts of 12 Xanthoria,sevenXanthomendoza, two Teloschistes species and Josefpoeltia parva (all Teloschistaceae) were analyzed. Xanthoria parietina was sampled on four conti- nents. More than 300 photobiont isolates were brought into sterile culture. The nuclear ribosomal internal transcribed spacer region (nrITS; 101 sequences) and the large subunit of the RuBiSco gene (rbcL; 54 sequences) of either whole lichen DNA or photobiont isolates were phylogenetically analyzed. ITS and rbcL phylogenies were congruent, although some subclades had low bootstrap support. Trebouxia arboricola, T. decolorans and closely related, unnamed Trebouxia species, all belong- ing to clade A, were found as photobionts of Xanthoria species. Xanthomendoza species associated with either T. decolorans (clade A), T. impressa, T. gelatinosa (clade I) or with an unnamed Trebouxia species. Trebouxia gelatinosa genotypes (clade I) were the photobionts of Teloschistes chrysophthalmus, T. hosseusianus and Josefpoeltia parva. Only weak correlations between distribution patterns of algal geno- types and environmental conditions or geographical location were observed. Key words: Asterochloris, Josefpoeltia parva, nrITS, rbcL, Teloschistes, Xanthomendoza, Xanthoria Accepted for pubication 10 October 2013 Introduction ters (morpho- and chemospecies). Morpho- logical criteria also formed the basis of species Lichens, as found in nature, are the symbiotic descriptions in lichen photobionts. In less phenotype of lichen-forming fungi in associa- than 2% of the c. 13 500 species of lichen- tion with their photoautotrophic partner. Spe- forming fungi known to science has the pho- cies names of lichens refer to the fungal part- tobiont ever been identified at species level ner. Lichen photobionts, mostly green algae (Honegger 2008); this estimate is based on or cyanobacteria, very rarely Xanthophyceae Tschermak-Woess (1988) and on the recent or Phaeophyceae (Tschermak-Woess 1988; literature. Persˇoh et al. 2004), have their own names As lichen-forming fungi do not easily re- and phylogenies. Traditionally, species of lichenize under sterile culturing conditions, lichen-forming fungi were described on the the range of compatible photobiont taxa per basis of morphological and chemical charac- lichen-forming fungal species cannot be ex- perimentally approached with re-licheniza- tion experiments in the Petri dish. Instead, the photobiont of lichen specimens, as col- S. Nyati, S. Scherrer and R. Honegger (corresponding lected in the wild, is investigated. Tradition- author): Institute of Plant Biology, University of Zu¨rich, ally, isolation and culturing under defined Zollikerstrasse 107, CH-8008, Zu¨rich, Switzerland. sterile conditions, followed by light or elec- Email: [email protected] S. Nyati: Department of Radiation Oncology, University tron microscopic analysis and comparison of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michi- with reference strains, were used (Ahmadjian gan 48109, USA. 1958, 1967; Tschermak-Woess 1988). Ac- S. Scherrer: Natural History Museum Winterthur, 8402 cordingly, only a few experts worldwide were Winterthur, Switzerland. S. Werth: Faculty of Life- and Environmental Sciences, able to identify the photobionts of lichen- University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland. forming fungi at species level. Since the 190 THE LICHENOLOGIST Vol. 46 advent of molecular techniques, the time- ceptable partners of lichen-forming fungi consuming isolation and culturing has been (Tschermak-Woess 1988; Persˇoh et al. 2004). largely avoided; instead, photobiont-specific More than 80% of the lichen-forming molecular markers applied to whole lichen fungi studied associate with green algal photo- DNA has facilitated photobiont identifica- bionts, representatives of the genera Trebouxia tion at the species level (Kroken & Taylor de Puymaly and Asterochloris (Tscherm.- 2000; Dahlkild et al. 2001; Helms et al. 2001; Woess) T. Friedl ined.(Trebouxiophyceae Piercey-Normore & DePriest 2001; Tibell sensu Friedl 1995) being the most common 2001; Romeike et al. 2002; Tibell & Beck and widespread partners in all climates 2002; Helms 2003; Piercey-Normore 2004, (Ahmadjian 1988; Tschermak-Woess 1988; 2006; Yahr et al. 2004, 2006; Blaha et al. Rambold et al. 1998; Persˇoh et al. 2004; Beck 2006; Guzow-Krzeminska 2006; Muggia et &Persˇoh 2009). Probably due to their ability al. 2008, 2010; Francisco De Oliveira et al. to survive desiccation unharmed, Trebouxia 2012). Based on increasing numbers of spp. are the photobionts of most lichen- entries in databases, the studies above have forming fungi in climatically extreme habi- gained novel insights into photobiont diver- tats such as Antarctic, Arctic, alpine or desert sity and phylogenies. Isolation and culturing ecosystems, where the whole thallus is con- are, however, still crucial as reference mate- tinuously subjected to drought and tempera- rial, for genetic analyses at the subspecific ture extremes. level and for diverse experimental approaches. Sexually reproducing lichen-forming fungi The range of compatible photoautotrophic are assumed to re-lichenize at each repro- partners per fungal species and their inter- ductive cycle, that is germinating asco- or and intraspecific diversity are ideally studied basidiospores have to find a compatible pho- in a large set of samples from a wide geo- tobiont. Contradictory views are found in the graphical range. However, even the analysis literature concerning the abundance of free- of one or a few samples gives valuable first in- living Trebouxia cells and their availability sights into the taxonomic affiliation of compat- for asco- or basidiospore-derived germlings ible photobionts. The majority of morphologi- of lichen-forming fungi. According to Ah- cally advanced species of lichen-forming fungi madjian (1988, 2002a, b), Trebouxia species are moderately specific to specific with regard do not normally exist outside lichen thalli. to their photobiont selection, that is a fungal Tschermak-Woess (1978) found free-living species associates with one or few species Trebouxia cells, but pointed out that they are of green algae or cyanobacteria (Honegger rare in aerophilic algal communities. Bubrick 1993). A lower specificity towards their pho- et al. (1984) found free-living Trebouxia cells tobiont was observed in a few of the lichen- near thalli of Xanthoria parietina, and accord- forming ascomycetes forming morphologi- ing to Mukhtar et al. (1994) Trebouxia arbor- cally less advanced crustose thalli (Friedl icola de Puymaly is one of the most common 1987; Tschermak-Woess 1988; Beck 2002; colonizers of bare rock surfaces after fires in Helms 2003; Blaha et al. 2006; Pe´rez-Ortega Israel. In a series of elegant in situ re-licheni- et al. 2012; but see Vargas Castillo & Beck zation studies, Sanders (2005) observed large 2012). Moreover, lichen mycobionts grow- numbers of free Trebouxia cells on plastic ing in extreme habitats such as Antarctic or slides which had been exposed in oak trees alpine ecosystems tend to associate with a (Quercus ilex) with lichen cover in Spain, and wide range of photobiont strains (Romeike germ tubes of Xanthoria parietina ascospores