Extremely low genetic diversity of Stigonema associated with Stereocaulon in eastern Canada

Lavoie, Camille; Renaudin, Marie; McMullin, Richard Troy; Gagnon, J. D.; Roy, Claude; Beaulieu, Marie-Ève; Bellenger, Jean‐Philippe; Villarreal, Juan Carlos

doi:10.1639/0007-2745-123.2.188

Cited by 13 publications

(8 citation statements)

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“…Recent molecular analyses have shown an extremely low genetic diversity in Stigonema across temperate, boreal and tundra biomes (Lavoie et al . 2020), without mycobiont specificity. The vnfDG sequences from Stigonema form a monophyletic group (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Unlike reindeer lichens, Stereocaulon species have a mutualistic association with cyanobacteria, mainly from the genus Stigonema, which are located in cephalodia (Huss-Danell 1977, 1979; Kershaw 1978; Kytöviita & Crittenden 2002; Lavoie et al . 2020). In Canada, acetylene reduction assays on Stereocaulon cyanobacteria have demonstrated their critical contribution to the nitrogen (N) budget (Crittenden & Kershaw 1978; Kershaw 1978).…”

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Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

2021

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Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

2021

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“…One might argue that the low genetic diversity of the Rhizonema photobionts was a by‐product of the short 16S fragment we obtained for a marker that is relatively conserved (Woese & Fox, 1977) and commonly used to infer broader cyanobacterial phylogenies (Elvebakk et al., 2008; Miadlikowska et al., 2014; O’Brien, 2013; O’Brien et al., 2005; Svenning et al., 2005). However, the rbc LX, another marker frequently employed in cyanobacterial phylogenetics (Lavoie et al., 2020; Magain et al., 2017, 2018; Miadlikowska et al., 2014; O’Brien et al., 2005, 2013), also exhibited low divergence for those samples where it could be amplified. Even the longer pieces of 16S amplified for selected samples did not alter our conclusions about the phylogenetic structure in Rhizonema .…”

Section: Discussionmentioning

confidence: 99%

“…Studies of lichen photobionts have mostly focused on green‐algal photobionts in so‐called chlorolichens (Grande et al., 2018; Leavitt et al., 2015; Muggia et al., 2020), whereas studies of cyanolichens have been far more limited (e.g. Lavoie et al., 2020; Magain et al., 2017; Otálora et al., 2010). Cyanolichens are obligate associations between lichen‐forming fungi and cyanobacteria and can be classified into two artificial groups (Rikkinen, 2017): bipartite lichens, with one mycobiont and one cyanobacterial photobiont; and tripartite lichens, where one mycobiont associates simultaneously with a green‐algal and a cyanobacterial photobiont, either forming chimeric thalli (photosymbiodemes) or with the cyanobionts restricted to cephalodia, pocket‐like structures in the thallus (Rikkinen, 2015).…”

Section: Introductionmentioning

confidence: 99%

Extensive photobiont sharing in a rapidly radiating cyanolichen clade

et al. 2020

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Recent studies have uncovered remarkable diversity in Dictyonema s.lat. basidiolichens, here recognized as subtribe Dictyonemateae. This group includes five genera and 148 species, but hundreds more await description. The photobionts of these lichens belong to Rhizonema, a recently resurrected cyanobacterial genus known by a single species. To further investigate photobiont diversity within Dictyonemateae, we generated 765 new cyanobacterial sequences from 635 specimens collected from 18 countries. The ITS barcoding locus supported the recognition of 200 mycobiont (fungal) species among these samples, but the photobiont diversity was comparatively low. Our analyses revealed three main divisions of Rhizonema, with two repeatedly recovered as monophyletic (proposed as new species), and the third mostly paraphyletic. The paraphyletic lineage corresponds to R. interruptum and partnered with mycobionts from all five genera in Dictyonemateae. There was no evidence of photobiont‐mycobiont co‐speciation, but one of the monophyletic lineages of Rhizonema appears to partner predominantly with one of the two major clades of Cora (mycobiont) with samples collected largely from the northern Andes. Molecular clock estimations indicate the Rhizonema species are much older than the fungal species in the Dictyonemateae, suggesting that these basidiolichens obtained their photobionts from older ascolichen lineages and the photobiont variation in extant lineages of Dictyonemateae is the result of multiple photobiont switches. These results support the hypothesis of lichens representing "fungal farmers," in which diverse mycobiont lineages associate with a substantially lower diversity of photobionts by sharing those photobionts best suited for the lichen symbiosis among multiple and often unrelated mycobiont lineages.

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“…The introduction of the term holobiont (Margulis, 1991) favoured the studies and promoted a holistic view on symbiotic interactions where several species are considered (Vandenkoornhuyse et al ., 2015; Faure et al ., 2018; Hassani et al ., 2018; Simon et al ., 2019). Among non-model organisms, lichens are the symbiotic organism “par excellence”, because of a partnership between fungi (one-several species), green algae, cyanobacteria and numerous bacteria in a multi-species symbiosis (Aschenbrenner et al ., 2016; Lavoie et al ., 2020). While the interactions between algae/cyanobacteria have been intensively studied, the role of bacteria in the symbiosis is still in its infancy (Grube et al ., 2015).…”

Section: Introductionmentioning

confidence: 99%

Geography, not host identity, shapes bacterial community in reindeer lichens

Alonso-García

Villarreal

2021

Preprint

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Background and AimsTremendous progress have been recently achieved in host-microbe research, however, there is still a surprising lack of knowledge in many taxa. Despite its dominance and crucial role in boreal forest, reindeer lichens have until now received little attention. We characterize, for the first time, the bacterial community of four species of reindeer lichens from Eastern North America’s boreal forests. We analysed the effect of two factors (host-identity and geography) in the bacterial community composition, we verified the presence of a common core bacteriota and identified the most abundant core taxa.MethodsMorphological and molecular lichen species delimitation was performed based on the ITS region. The bacterial community of around 200 lichen samples was characterised using the 16S rRNA gene.Key ResultsOur results showed that host-lichen identity does not determine bacterial community composition in reindeer lichens, but we confirmed the influence of geography in shaping the diversity and abundance of bacteria associated to the species Cladonia stellaris from lichen woodlands. We also revealed that reindeer lichens share a reduced common core bacteriota composed exclusively by Proteobacteria.ConclusionsThe bacterial community in reindeer lichens is not host-selective. Northern lichen woodlands exhibit a significant higher diversity and abundance of bacteria associated to Cladonia stellaris. Nevertheless, the specific role of those bacteria as well as the process of host colonization remains to be determined. Elucidating these two aspects would be key to have a better understanding of the whole boreal ecosystems. The reduced and not diverse core bacteriota of reindeer lichens might be due to the larger size of our study area. The presence of the species Methylorosula polaris in the core bacteriota is evident and might have a particular importance for reindeer lichens.

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Extremely low genetic diversity of Stigonema associated with Stereocaulon in eastern Canada

Cited by 13 publications

References 53 publications

Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

Extensive photobiont sharing in a rapidly radiating cyanolichen clade

Geography, not host identity, shapes bacterial community in reindeer lichens

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