About this Research Topic
Lichens are iconic examples of specialized symbioses between fungi (the mycobionts) and green or blue green algae (the photobionts). Both mycobionts and photobionts show different level of selectivity and specify towards each other. Notwithstanding that dual nature of lichens is known for more than 100 years, still several questions related to lichenization remain unanswered, such as the diversity of lichenized photobionts within lichen thalli and potential photobiont switch between thalli of different species, the ecological factors determining the biogeography and spatial distribution of both symbionts, as well as still uncovered phylogenetic relationships.
This Research Topic issue aims at deepening the knowledge on the phylogenetic relationships of lichen photobionts and their genetic diversity, as well to studying their taxonomy, specificity and selectivity patterns of association with the fungal partners, their biogeography and diversity at global and local scales, the influence of environmental factors on their diversity within individual lichen thalli and within lichen community, or geographical region and their physiological responses to environmental stresses. Several achievements have been performed to broaden the knowledge on lichen photobionts, numerous new phylogenetic lineages have been discovered but only few of them have been characterized in their cell morphology, ultrastructure and physiology so far. Therefore, there is still much to be discovered in particular from those habitats that are still poorly investigated and under-sampled, such as tropical regions or habitats characterized by extreme conditions.
This Research Topic, dedicated to the diversity of the lichen photobiont partners, will comprise the following topics:
• Phylogeny and taxonomy of lichen photobionts
• Diversity of photobionts at global and local scales
• Specificity and selectivity of photobionts and their fungal partners in lichen symbiosis
• Biogeography photobionts in relation to their fungal partners
• The influence of external factors on photobiont diversity within lichen thalli (using metabarcoding techniques) and within lichen communities
Keywords: cyanobacteria, green algae, lichenized fungi, phylogenetic relationships, specificity
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