Light color acclimation is a key process in the global ocean distribution ofSynechococcus cyanobacteria

Abstract

Marine cyanobacteria are major contributors to global oceanic primary production and exhibit a unique diversity of photosynthetic pigments, allowing them to exploit a wide range of light niches. However, the relationship between pigment content and niche partitioning has remained largely undetermined due to the lack of a single-genetic marker resolving all pigment types (PTs). Here, we developed and employed a robust method based on three distinct marker genes (, , and) to estimate the relative abundance of all known PTs from metagenomes. Analysis of the Oceans dataset allowed us to reveal the global distribution of PTs and to define their environmental niches. Green-light specialists (PT 3a) dominated in warm, green equatorial waters, whereas blue-light specialists (PT 3c) were particularly abundant in oligotrophic areas. Type IV chromatic acclimaters (CA4-A/B), which are able to dynamically modify their light absorption properties to maximally absorb green or blue light, were unexpectedly the most abundant PT in our dataset and predominated at depth and high latitudes. We also identified populations in which CA4 might be nonfunctional due to the lack of specific CA4 genes, notably in warm high-nutrient low-chlorophyll areas. Major ecotypes within clades I-IV and CRD1 were preferentially associated with a particular PT, while others exhibited a wide range of PTs. Altogether, this study provides important insights into the ecology of and highlights the complex interactions between vertical phylogeny, pigmentation, and environmental parameters that shape community structure and evolution.

Changes in water color shift competition between phytoplankton species with contrasting light‐harvesting strategies

“…As predicted, these two genera coexist in many regions across the global ocean but their distributions do not completely overlap (Ting et al 2002, Flombaum et al 2013. In agreement with the model predictions, Prochlorococcus uses chlorophyllbased light-harvesting antennae and is particularly abundant in blue waters of the oligotrophic subtropical gyres (Partensky et al 1999, Biller et al 2015, whereas the PBS-containing Synechococcus prevails in slightly more turbid oceanic and coastal waters dominated by greenish blue and green light (Scanlan and West 2002, Ting et al 2002, Gr ebert et al 2018. Moreover, the highly diverse Synechococcus genus comprises several pigment types, that have branched out over a wide range of aquatic ecosystems in accordance with the underwater light colors that can be captured by their phycobili-pigments (Stomp et al 2007, Gr ebert et al 2018).…”

Ecological and genomic features of two widespread freshwater picocyanobacteria

“…The same study shed light on the flexible genome of marine picocyanobacteria, showing genomic islands and hypervariable regions containing genes involved in LPS synthesis, ABC transporters, transcriptional regulators, DNA mobility or phage defence systems (Dufresne et al ., ). One of these islands contains the genes for PBS synthesis and regulation, a feature that allows Synechococcus to adapt to different light conditions, with some strains being chromatic adaptors (Six et al ., ) that are ecologically abundant (Grébert et al ., ). Distribution patterns of different marine Synechococcus ecotypes revealed open ocean, coastal and opportunistic specialists (Dufresne et al ., ; Zwirglmaier et al ., ; Sohm et al ., ).…”

“…In the oceans, microdiverse Synechococcus lineages inhabit different regions of the globe across large spatial scales (Zwirglmaier et al, 2008;Farrant et al, 2016), allowing this genus to occupy virtually all ocean waters. One important picocyanobacterial phenotypic characteristic is their accessory pigment composition (presence of various combinations of phycoerythrin and phycocyanin in their phycobilisomes, hereafter PBS), which makes them efficient light harvesters, photosynthesizing at different depths and across a range of light intensities (Vörös et al, 1998;Stomp et al, 2007;Grébert et al, 2018).…”

Biogeographic variations of picophytoplankton in three contrasting seas: the Bay of Bengal, South China Sea and Western Pacific Ocean

“…Pro and Syn are both ecologically dominant and widespread members in warm oligotrophic waters (Liu et al 2007, Seymour et al 2010, although Pro are gen-erally more abundant than Syn and PEuks, often by 10-fold or more in the open ocean (Jiao & Yang 2002, Flombaum et al 2013. Furthermore, Syn and PEuks have a wide geographical distribution that covers both oligo-and mesotrophic oceanic and coastal areas from pole to pole (Olson et al 1990, Flombaum et al 2013, Grébert et al 2018. Observations in the oligotrophic Pacific Ocean and Atlantic Ocean have revealed that picophytoplankton can account for approximately 60−80% of the total primary produc-tivity (Campbell et al 1997, Grob et al 2011.…”