Distinctive characters of Nostoc genomes in cyanolichens

• Published in: BMC Genomics
• Main Authors: Gagunashvili, Andrey, Andrésson, Ólafur
• Other Authors: Líf- og umhverfisvísindadeild (HÍ), Faculty of Life and Environmental Sciences (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Nature 2018
• Subjects: Cyanobacteria; Nostoc; Lichen; Symbiosis; Symbiotic competence; Gerlar; Samlífi; Fléttur (plöntur); Iceland
• Online Access: https://hdl.handle.net/20.500.11815/924; https://doi.org/10.1186/s12864-018-4743-5

Publisher's version (útgefin grein) Background Cyanobacteria of the genus Nostoc are capable of forming symbioses with a wide range of organism, including a diverse assemblage of cyanolichens. Only certain lineages of Nostoc appear to be able to form a close, stable symbiosis, raising the question whether symbiotic competence is determined by specific sets of genes and functionalities. Results We present the complete genome sequencing, annotation and analysis of two lichen Nostoc strains. Comparison with other Nostoc genomes allowed identification of genes potentially involved in symbioses with a broad range of partners including lichen mycobionts. The presence of additional genes necessary for symbiotic competence is likely reflected in larger genome sizes of symbiotic Nostoc strains. Some of the identified genes are presumably involved in the initial recognition and establishment of the symbiotic association, while others may confer advantage to cyanobionts during cohabitation with a mycobiont in the lichen symbiosis. Conclusions Our study presents the first genome sequencing and genome-scale analysis of lichen-associated Nostoc strains. These data provide insight into the molecular nature of the cyanolichen symbiosis and pinpoint candidate genes for further studies aimed at deciphering the genetic mechanisms behind the symbiotic competence of Nostoc. Since many phylogenetic studies have shown that Nostoc is a polyphyletic group that includes several lineages, this work also provides an improved molecular basis for demarcation of a Nostoc clade with symbiotic competence. This research was funded by the Icelandic Research Fund RANNIS (project number 134055-051) and by the University of Iceland. Sample collection, study design, analysis, data interpretation and manuscript writing was carried out by the authors. Peer Reviewed