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.

一些蓝细菌使用可见光谱之外的光进行有氧光合作用。远红光 (FRL) 区域可通过复杂的驯化过程进入，该过程涉及形成新的藻胆体和含有叶绿素f的光系统。从单细胞到分支丝状形式的多种蓝细菌显示出这种反应。这些生物已从遮蔽环境中分离出来，例如微生物垫、土壤、岩石和叠层石。然而，自然界中含有叶绿素f的物种的全面传播仍然未知。目前，发现新的叶绿素f蓝细菌涉及在选择性远红光下长时间的孵育。我们使用标记基因检测叶绿素f环境样本和宏基因组数据中的生物。该标记apcE2编码与 FRL 光合作用相关的藻胆体接头。通过关注序列内的远红基序，简并 PCR 和 BLAST 搜索可以有效区分正常的叶绿素a相关apcE 。即使是很短的恢复序列也能携带足够的信息用于系统发育定位。叶绿素f标志物在来自全球不同环境的宏基因组数据集中发现了光合作用，包括蓝藻共生体、高盐湖、珊瑚和北极/南极地区。这些额外的信息支持更高的系统发育分辨率，支持垂直下降而不是水平基因转移在很大程度上导致这种表型分布的假设。