Global Biodiversity Patterns of the Photobionts Associated with the Genus Cladonia (Lecanorales, Ascomycota)

Abstract

The diversity of lichen photobionts is not fully known. We studied here the diversity of the photobionts associated with Cladonia, a sub-cosmopolitan genus ecologically important, whose photobionts belong to the green algae genus Asterochloris. The genetic diversity of Asterochloris was screened by using the ITS rDNA and actin type I regions in 223 specimens and 135 species of Cladonia collected all over the world. These data, added to those available in GenBank, were compiled in a dataset of altogether 545 Asterochloris sequences occurring in 172 species of Cladonia. A high diversity of Asterochloris associated with Cladonia was found. The commonest photobiont lineages associated with this genus are A. glomerata, A. italiana, and A. mediterranea. Analyses of partitioned variation were carried out in order to elucidate the relative influence on the photobiont genetic variation of the following factors: mycobiont identity, geographic distribution, climate, and mycobiont phylogeny. The mycobiont identity and climate were found to be the main drivers for the genetic variation of Asterochloris. The geographical distribution of the different Asterochloris lineages was described. Some lineages showed a clear dominance in one or several climatic regions. In addition, the specificity and the selectivity were studied for 18 species of Cladonia. Potentially specialist and generalist species of Cladonia were identified. A correlation was found between the sexual reproduction frequency of the host and the frequency of certain Asterochloris OTUs. Some Asterochloris lineages co-occur with higher frequency than randomly expected in the Cladonia species.

Microbial Communities of Cladonia Lichens and Their Biosynthetic Gene Clusters Potentially Encoding Natural Products

“…The major photobiont/phycobiont partner in our lichen specimens formed a group with the green algae species Asterochloris mediterranea , which has been identified from thalli of other Cladonia species [ 79 , 89 ]. Most Cladonia species are known to be associated with the different species of Asterochloris or rarely with Chlorella , while species of Trebouxia are generally absent [ 29 , 89 ]. In our analysis, a small portion of the ITS2 sequences (4% or 6550 of the green algae sequences) grouped with Trebouxia spp.…”

Lichen algae: the photosynthetic partners in lichen symbioses

“…Photobiont tolerance of heavy metals appears to influence their selection by mycobionts in some lichen communities colonizing metal-rich substrata (Vančurová et al 2018;Rola et al 2021) but not others (Beck 2002;Hauck et al 2007;Bačkor et al 2010). Many studies stress the intrinsic compatibility requirements of individual fungal taxa as primary determinants of pairing patterns (Yahr et al 2004;Stenroos et al 2006;Myllys et al 2007;Leavitt et al 2015;Joneson & O'Brien 2017), often in conjunction with ecological factors (Elvebakk et al 2008;O'Brien et al 2013;Dal Grande et al 2018;Jüriado et al 2019;Pino-Bodas & Stenroos 2020). In some communities, mycobionts may have adapted to utilize a common pool or pools of photobionts, whose local availability might thereby be sustained for all users (Beck et al 2002;Rikkinen et al 2002;Rikkinen 2003;Sanders et al 2016;Onuţ-Brännström et al 2018;Cardós et al 2019).…”

Choosing the Right Life Partner: Ecological Drivers of Lichen Symbiosis

“…In the study area, globally abundant Asterochloris species ( Asterochloris irregularis , A. pseudirregularis , A. lobophora , A. phycobiontica , A. gaertneri , A. friedlii , and others) were not detected. One of the most common Asterochloris species, A. glomerata ( Pino-Bodas and Stenroos, 2020 ), was present in three samples and belonged to the single genotype that is known to be exclusively from the study area.…”

“…Particular species of Cladonia , Lepraria , and Stereocaulon differ in their preferred Asterochloris species-level lineages (i.e., they are selective towards their phycobionts; Peksa and Škaloud, 2011 ; Škaloud et al, 2015 ; Steinová et al, 2019 ; Vančurová et al, 2020 ). A relatively high number of studies have focused on phycobionts of Cladonia , Lepraria , and Stereocaulon ; however, new phycobiont species-level lineages continue being discovered ( Moya et al, 2015 ; Vančurová et al, 2018 ; Pino-Bodas and Stenroos, 2020 ; Kosecka et al, 2021 ). In addition, other trebouxiophycean algal genera have been detected as phycobionts of Stereocaulon ( Beck, 2002 ; Vančurová et al, 2015 , 2018 , 2020 ; Kosecka et al, 2021 ), Cladonia ( Ahmadjian and Jacobs, 1981 ; Korchikov et al, 2018 ; Osyczka et al, 2020 ), and Lepraria ( Engelen et al, 2010 ).…”