Trebouxia lynnae sp. nov. (Former Trebouxia sp. TR9): Biology and Biogeography of an Epitome Lichen Symbiotic Microalga

Abstract

Two microalgal species, Trebouxia jamesii and Trebouxia sp. TR9, were detected as the main photobionts coexisting in the thalli of the lichen Ramalina farinacea. Trebouxia sp. TR9 emerged as a new taxon in lichen symbioses and was successfully isolated and propagated in in vitro culture and thoroughly investigated. Several years of research have confirmed the taxon Trebouxia sp. TR9 to be a model/reference organism for studying mycobiont–photobiont association patterns in lichen symbioses. Trebouxia sp. TR9 is the first symbiotic, lichen-forming microalga for which an exhaustive characterization of cellular ultrastructure, physiological traits, genetic and genomic diversity is available. The cellular ultrastructure was studied by light, electron and confocal microscopy; physiological traits were studied as responses to different abiotic stresses. The genetic diversity was previously analyzed at both the nuclear and organelle levels by using chloroplast, mitochondrial, and nuclear genome data, and a multiplicity of phylogenetic analyses were carried out to study its intraspecific diversity at a biogeographical level and its specificity association patterns with the mycobiont. Here, Trebouxia sp. TR9 is formally described by applying an integrative taxonomic approach and is presented to science as Trebouxia lynnae, in honor of Lynn Margulis, who was the primary modern proponent for the significance of symbiosis in evolution. The complete set of analyses that were carried out for its characterization is provided.

Patterns of Endemism in Lichens: Another Paradigm-Shifting Example in the Lichen Genus Xanthoparmelia from Macaronesia

“…No auxospores or sexual reproduction were observed. The taxonomic classification of the Trebouxiophyceae is mainly based on a phylogenetic approach, and its delimitation on the congruence of 18S rDNA sequence data [ 75 , 76 ]. In the way it is presently characterized, the class Trebouxiophyceae comprises a diverse range of unicellular, colonial, and multicellular algae, which are mainly found in freshwater and terrestrial ecosystems [ 77 , 78 ].…”

“…Owing to their simple morphology and small size, our understanding of the diversity within this class remains somewhat limited. It is very likely that many new taxa will be discovered, especially among the lichen photobionts, particularly within the “ Chlorella -like” group of lichenized algae [ 75 , 76 , 80 ]. The use of molecular and ultrastructural methodologies will be essential to carry out further research and to determine species or OTUs (operational taxonomic units) within this family.…”

Near-Infrared Metabolomic Fingerprinting Study of Lichen Thalli and Phycobionts in Culture: Aquaphotomics of Trebouxia lynnae Dehydration

“…-Trebouxia jamesii TR1, isolated from the lichen Ramalina farinacea from a population of Sierra El Toro (Castellón, Spain; 39 [17]. It has recently been renamed as Trebouxia lynnae [37].…”

“…TR9, isolated from the lichen Ramalina farinacea from a populatio Sierra El Toro (Castellón, Spain; 39°54′16″ N, 0°48′22″ W), previously describe Gasulla et al, [17]. It has recently been renamed as Trebouxia lynnae [37].…”

Microalgal and Nitrogen-Fixing Bacterial Consortia: From Interaction to Biotechnological Potential

“…Within the algae group, the unicellular ones are referred to as microalgae. Although primarily abundant in aquatic ecosystems, microalgae can also thrive in various other habitats, such as terrestrial environments, within the crowded rhizosphere [2], in lichens [3], and even inside animal as in coral reefs [4]. Additionally, microalgae have been found on glaciers and ice sheets [5].…”