What makes red algae so different and why should we care?

From Eurekalert

Carnegie Institution for Science


IMAGE: Porphyra clinging to rocks in Germany’s Heligoland. It thrives in the harsh habitat of the intertidal zone, where it is exposed to fluctuating temperatures, high UV radiation, severe salt stress,… view more

Credit: By Gabriele Kothe-Heinrich

Palo Alto, CA– The red algae called Porphyra and its ancestors have thrived for millions of years in the harsh habitat of the intertidal zone–exposed to fluctuating temperatures, high UV radiation, severe salt stress, and desiccation.

Red algae comprise some of the oldest non-bacterial photosynthetic organisms on Earth, and one of the most-ancient of all multicellular lineages. They are also fundamentally integrated into human culture and economics around the globe. Some red algae play a major role in building coral reefs while others serve as “seaweed” foods that are integral to various societies. Porphyra is included in salads (as are related genera of algae), is called “nori” in Japan, where it is used to wrap sushi, and “laver” in Wales, where it is a traditional and nutritious food ingredient.

Despite Porphyra‘s ecological, evolutionary, and commercial importance, there is still relatively little known about its molecular genetics and physiology.

That’s why a team of plant scientists, including Carnegie’s Arthur Grossman, sequenced and analyzed the complete genome of the red algae Porphyra umbilicalis. The genetic makeup of this extraordinarily hardy organism has provided researchers with a better understanding of red algal evolution and the ways in which these organisms cope with their brutal intertidal habitat.

Their findings are published by Proceedings of the National Academy of Sciences.

The team’s analysis showed that Porphyra and other red algae have minimal structural elements that make up their cellular cytoskeletons as compared to other types of multicellular organisms. This may explain why the multicellular red algae tend to be “small” in stature.

Likewise, the team found genes for cellular processes that help Porphyra and its ancestors survive under extreme duress–including “sunscreen”-like compounds for protection from UV radiation and other compounds that allow them to withstand desiccating conditions, in addition to various proteins that ameliorate the potentially toxic consequences of absorbing strong sunlight. Furthermore, the extremely resilient, flexible walls of Porphyra cells allow them to dramatically change their volume as they lose water when they are baking in the sun and drying in the winds, and to withstand the forces of beating waves.

“The information we gleaned from the Porphyra genome shows us just how different red algae are,” Grossman explained. “But it is also interesting to note that organisms evolutionarily related to the red algae have had profound impacts on human health and marine ecosystems.”

For example, one group of organisms that evolved from the red algae, the apicomplexans, is non-photosynthetic and includes the plasmodium parasites that cause malaria. Another algal group that evolved from the red algae, the dinoflagellates, is responsible for toxic red tides, but is also the provider of nutrients that sustain corals, which serve as the foundation of reefs (which are homes for numerous animals).

As Grossman states, “As we learn more about the different algal groups and their evolutionary histories, we are learning more about the biotic pillars that continue to be a major foundation for sustaining and shaping life on our planet.”


Sequencing and assembly of the Porphyra genome were provided by the Joint Genome Institute (U. S. Dept. of Energy) under a Community Science Program award from the Office of Science of the U. S. Dept of Energy. Other major research support was provided by NSF and NOAA.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

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42 thoughts on “What makes red algae so different and why should we care?

  1. Small biota account for most of the life on the planet. link Bacteria, for instance, weigh about 3000 times as much as all the humans.

      • Humans contain ten times as many bacterial and human cells, but the human eukaryotic cells are a lot bigger than bacteria.

        From the very beginning of eukaryotes, symbiosis has been the name of the game. The nucleus of eukaryotic cells evolved from viruses (probably), our mitochondria and other plastid organelles from bacteria and of course the chloroplasts of algae and plants from cyanobacteria. So eukaruotes formed from endosymbiosis of archaea with viruses and bacteria. The lineage of archaea from which we sprang has been observed only in its DNA. Actual, living organisms haven’t been found yet.

        The earliest metazoans (animals) were sponges, which often host so many symbiotic cyanobacteria that they are net producers of oxygen, their need for which has been found to be shockingly low. And most of their animal descendants have always relied upon symbiotic bacteria ever since.

      • Red algae evolved from three endosymbiotic events. The first was the original endosymbiosis of an archaean with a bacterium, which became the mitochondria, and the other combinations which came together to form the first eukaryote (arguably more than one event). The second was the endosymbiotic event combining a eukaryote with a cyanobacterium, which became the chloroplast and gave rise to all algae and plants. The third was a further endosymbiosis of the ancestral red alga with a heterotrophic eukaryote, somewhat akin to how lichen form from the association of a photosynthesizer with a fungus, or to the “plant-animal” association of corals.

      • @Gloateus:

        I’ve proposed that cellular life began in mud goo puddles as a soup of active parts, only later forming into cells. That lets different chemical paths and organelles evolve separately, only later working out cell walls, active transport, etc.


        It explains much, including why life uses so much potassium instead of sodium and likes the trace minerals it does. Life does not need to start as cells, but as a soup pot of goo. Then the bits get packaged into full batches in a cell later… which batches we see in the cells as organelles, nucleus, mitochondria, etc.

      • EM,

        If the origin of life went through an early precellular stage, it would have occurred long before the evolution of eukaryotic cells from the endosymbiosis of prokaryotic cells, ie archaea and bacteria, with possibly also a virus thrown in.

        Protocells evolved around four billion years ago, possibly from a precellular stage similar to what you suggest, but prokaryotes soon developed shortly thereafter. The date of origin of eukaryotes is not well constrained, but certainly before 1.6 Ga, based upon fossils, and possibly 2.7 Ga, based upon biochemical marker steranes.

      • Gloateus July 19, 2017 at 11:14 am

        For “bacterial and human”, please read “bacterial than human”.

      • Not only bacteria, also amoebas, fungi and mites. Think of yourself as a complex ecosystem with thousands of species.

      • As for human culture and technology, I can’t help thinking most if not all of our accomplishments are but an imitation or a variation of what nature and life already has invented long before us in a most ingenious and superior way. Are we really that special?

      • TTY,

        As a teenager, I read “Life on Man”. In college I explained my lack of hygiene was because I wanted to preserve the precious, precarious ecosystem of my skin, in hopes that good microbes, etc, would stay in balance with the bad, which could be upset by soap and water. But my then GF laid down the law with an ultimatum.

      • Gloateus July 19, 2017 at 11:14 am

        A rise in the levels of oxygen in the oceans and air seemed like a simple, convincing explanation for the evolution of animals, but Neoproterozoic reality was probably more complex than that.

        Not only did the first animals probably need very little oxygen, but if the protosponges did as do modern sponges, then their cyanobacterial symbionts could have provided them with most if not all of their oxygen requirements locally, regardless of the average content of the ancient seas.

        Oxygen requirements of the earliest animals


    • Check this out: “…The number of bacterial cells alone estimated to inhabit the Earth’s soils is staggering—2.6 x 10^29. ….”

    • I agree.
      I recently visited the Point Bonita Lighthouse. The lighthouse is located at Point Bonita at the San Francisco Bay entrance in the Marin Headlands near Sausalito, California. I was surprised to discover a bright red lichen like growth on the rock faces near the lighthouse.

      The conditions described in this article are very similar to the lighthouse area. It may have been Red Algae but it wasn’t at the waters edge so maybe not. It’s a mystery.

      • Mystery solved:
        “This furry alga (Trentepehlia) grows at Point Reyes on the shadier north face of rocks. Although it contains green chlorophyll, red pigments predominate. Algae such as these, called “rock violets”, need no soil.”

    • Photosynthetic life? I guess missing carbon is now passe. Life responds to its environment and with rising carbon dioxide, study of all photosynthetic life is crucial. Many CAGW acolytes have the gaia tainted worship of trees as the primary producers of oxygen when the reality is most oxygen comes from single cell organisms.
      The first organisms postulated in the oxygen catastrophe as producers of oxygen are stromatalites. The oxygen turned the seas blue from green, oxidizing iron to rust and forming banded iron sediments.

    • How does research which doesn’t mention climate change get funded?

      Maybe the grant application did mention how red algae have survived going on two billion years of climate change, hence need to be studied.

      • Maybe it’s supposed to a good news story. Red algae … “survive under extreme duress” …and..”withstand dessicating conditions”. So, as all the other plant life burns to a crisp and blows away in the wind, still there and different will be the red algae

      • Moira,

        Wouldn’t be surprised if the authors actually did pitch their project in those terms.

  2. population is inversely proportional to size so its not surprising about the quantity, research like this just re-enforces the old adage “the more we learn the less we know”.
    if I ever retire I`d like to do research into research

  3. As we begin to learn about all the various species on earth we are continually humbled by the vast amount of knowledge we simply do not have.
    Then along comes some imbecilic do-gooder proclaiming we are entering a great mass extinction where half of all species will become extinct, and further displays his ignorance (and lack of sense).
    We do not know how many species occupy earth, so how do we know how many is half of them?

  4. The caption says, “… where it is exposed to …, high UV radiation,…” High relative to what? If it was on top of Mt. Everest I’d agree that the UV flux was high compared to what is typical on Earth. However, at sea level, UV is as low as it gets above water. The UV exposure is elevated compared to that received by marine organisms that remain submerged. However, I don’t think that it rises (pun intended) to the level of “high.”

  5. Malaria is an evolved algae? Wow! Who knew.. mobile infective algae… makes me think, with that degree of change, more change could eventually lead to intelligent algae… or maybe it already has ;-)

    • Algae seem unlikely to invent neurons, so algal intelligence would be an evolutionary longshot, but who knows?

    • The text at the very least overstates the case by saying that plasmodia evolved from red algae. In one sense, they did, since their ancestor engulfed and encorporated an endosymbiont red alga, but that would be like saying that all eukaryotes evolved from a bacterium rather than an archaean, since our ultimate archaean ancestor similarly engulfed a bacterium, which evolved into our mitochondria. A more accurate statement would be that plasmodia and similar alvelolate, apicomplexan parasites evolved from the endosymbiosis of an ancestral, SAR supergroup eukaryote with another eukaryote, ie a red alga.

      A common red algal origin of the apicomplexan, dinoflagellate, and heterokont plastids


      The discovery of a nonphotosynthetic plastid in malaria and other apicomplexan parasites has sparked a contentious debate about its evolutionary origin. Molecular data have led to conflicting conclusions supporting either its green algal origin or red algal origin, perhaps in common with the plastid of related dinoflagellates. This distinction is critical to our understanding of apicomplexan evolution and the evolutionary history of endosymbiosis and photosynthesis; however, the two plastids are nearly impossible to compare due to their nonoverlapping information content. Here we describe the complete plastid genome sequences and plastid-associated data from two independent photosynthetic lineages represented by Chromera velia and an undescribed alga CCMP3155 that we show are closely related to apicomplexans. These plastids contain a suite of features retained in either apicomplexan (four plastid membranes, the ribosomal superoperon, conserved gene order) or dinoflagellate plastids (form II Rubisco acquired by horizontal transfer, transcript polyuridylylation, thylakoids stacked in triplets) and encode a full collective complement of their reduced gene sets. Together with whole plastid genome phylogenies, these characteristics provide multiple lines of evidence that the extant plastids of apicomplexans and dinoflagellates were inherited by linear descent from a common red algal endosymbiont. Our phylogenetic analyses also support their close relationship to plastids of heterokont algae, indicating they all derive from the same endosymbiosis. Altogether, these findings support a relatively simple path of linear descent for the evolution of photosynthesis in a large proportion of algae and emphasize plastid loss in several lineages (e.g., ciliates, Cryptosporidium, and Phytophthora).

      • Another correct way of putting it would be to say that plastids in Plasmodium and its kin descended from a red alga, while the whole organism descends from a different eukaryote line.

  6. What is this? usually the operators of the site throw ‘red meat’ to the hordes of commenters.

    red algae?

    must be on a health kick

    • Spirulina would be even worse.

      Green Meanies would have us all subsisting on pond scum if they could.

      With insects on feast days.

    • Except that Chlamydomonadaceae is a family of green algae (Phylum Chlorophyta) that happens to have some red pigment, rather than a member of the red algae (Division Rhodophyta).

      And no, I wouldn’t recommend eating the red snow or ice.

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