Global distribution of a chlorophyll f cyanobacterial marker

• Published in: The ISME Journal
• Main Authors: Antonaru, Laura A., Cardona, Tanai, Larkum, Anthony W. D., Nürnberg, Dennis J.
• Format: Text
• Language: English
• Published: Nature Publishing Group UK 2020
• Subjects: Article; Antarctic; Arctic; Antarc*
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7608106/; http://www.ncbi.nlm.nih.gov/pubmed/32457503; https://doi.org/10.1038/s41396-020-0670-y

Some cyanobacteria use light outside the visible spectrum for oxygenic photosynthesis. The far-red light (FRL) region is made accessible through a complex acclimation process that involves the formation of new phycobilisomes and photosystems containing chlorophyll f. Diverse cyanobacteria ranging from unicellular to branched-filamentous forms show this response. These organisms have been isolated from shaded environments such as microbial mats, soil, rock, and stromatolites. However, the full spread of chlorophyll f-containing species in nature is still unknown. Currently, discovering new chlorophyll f cyanobacteria involves lengthy incubation times under selective far-red light. We have used a marker gene to detect chlorophyll f organisms in environmental samples and metagenomic data. This marker, apcE2, encodes a phycobilisome linker associated with FRL-photosynthesis. By focusing on a far-red motif within the sequence, degenerate PCR and BLAST searches can effectively discriminate against the normal chlorophyll a-associated apcE. Even short recovered sequences carry enough information for phylogenetic placement. Markers of chlorophyll f photosynthesis were found in metagenomic datasets from diverse environments around the globe, including cyanobacterial symbionts, hypersaline lakes, corals, and the Arctic/Antarctic regions. This additional information enabled higher phylogenetic resolution supporting the hypothesis that vertical descent, as opposed to horizontal gene transfer, is largely responsible for this phenotype’s distribution.