Super seaweed: ECU biologist helps unravel secrets of algae genome

[USA] People who enjoy exploring coastal tidal pools and observing the primordial soup from which life on land emerged find any number of fascinating creatures hidden among the algae-coated rocks. But it is the algae that most fascinates East Carolina University biologist John Stiller, to the potential benefit of the multi-billion dollar international aquaculture industry and a hungry world population.

Stiller, an associate professor of plant genomics who specializes in the study of molecular evolution and algal genomics, served as a primary researcher on a 50-member team led by the University of Maine, the Carnegie Institution for Science and ECU that sequenced and analyzed the genome of Porphyra umbilicalis, a red alga (think the black stuff wrapped around sushi) that lives in the rocky intertidal zone, one of the most dynamic and difficult habitats on the planet. These algae are thought to represent one of the oldest forms of marine life — and a major international food source.

Red algae, known as Porphyra umbilicalis, is the subject of newly published genomic research by ECU professor John Stiller. the hardy sea plant grows in coastal tidal pools and is used internationally for food.
©/Contributed photo

Stiller and his colleagues conducted the research work for the U.S. Department of Energy Joint Genome Institute, supported by the National Science Foundation, National Oceanic and Atmospheric Administration. Their findings were published in June by the National Academy of Science under the title, ‘Insights into the red algae and eukaryotic evolution from the genome of Porphyra umbilicalis.”

In the high intertidal zone it occupies, Porphyra is exposed daily and seasonally to a wide variety of environmental stresses, Stiller told The Daily Reflector. On one day, it may be immersed in seawater in the morning, then fully exposed to baking sun and drying winds at low tide in the afternoon. The next day, it could rain during low tide, meaning Porphyra blades must adjust to a large change in salinity in just a few minutes after the tide recedes. In colder months, low tides can bring snow and freezing temperatures.

“Porphyra is one of the few algae, or organisms of any kind for that matter, that can thrive in these kinds of conditions,” Stiller said. “Moreover, it has managed to persist in this environment through every mass extinction in the earth’s history, including the great Permian extinction that wiped out 80 percent of the planet’s species, and the end Cretaceous event that was responsible for the death of the dinosaurs.”

Despite where it lives, Porphyra has avoided the same fates, and the analysis of the genome that Stiller and his teammates studied provides new insights into the metabolic pathways that allow it to be so adaptable and flexible.

While there is an increasing interest in algae as an energy source, Porphyra has not been targeted as a source of biofuels because it is relatively low in fats, Stiller said. It is, however, a major source of food in maritime communities of Asia and Europe, and is the basis for an international aquaculture industry that generates billions of dollars annually.

“It’s been more of a specialty item in the US, but its popularity is growing, largely because of its health properties,” Stiller said. “Personally, I don’t like the taste and don’t eat it myself.”

Porphyra is extremely rich in protein, vitamin C, vitamin B-12 and other antioxidants, but low in fats. Tracing the genome sequence provides a much clearer understanding of how Porphyra grows and of the metabolic pathways responsible for its exceptional nutritional properties, meaning researchers will be able to better manipulate growth conditions and genetic properties to further improve yields and nutrient content, the ECU scientist said.

“The genome is an important resource for most research on algae and plants for human use,” Stiller said. “Understanding how to improve stress tolerance is valuable for many algae/plants used in agriculture and other human and societal enterprises. This is where our alga really shines.”

Even if, like Stiller, you don’t like the taste of seaweed, imagine, as Stiller does, a future in which Porphyra’s desirable genetic properties might be instilled in land crops to give them the ability to resist and survive drought, flood, cold, heat and other conditions the way it does.

Algae are particularly valuable for scientific study because they are old — really old — from the perspective of plant and animal life.

“A close relative of Porphyra umbilicalis, the species we studied, has been identified in the fossil record from over a billion years ago,” Stiller said.

Though red algae are one of the oldest multicellular lineages, only a few have had their genomes sequenced, according to information distributed by the Energy Department.

Because of Stiller’s knowledge and experience, ECU is one of three lead institutions in the Porphyra genome sequencing project. Along with Susan Brawley at the University of Maine and Arthur Grossman at the Carnegie Institute at Stanford University, Stiller was one of the three principal investigators on the Community Sequencing Grant from the Department of Energy Joint Genomics Institute, which funded and carried out the core sequencing and computational assembly of the genome.

“It is remarkable that this organism has lived this long and spread to other organisms that are the basis of the air we breathe and the energy sources for all marine life,” Stiller said. “To be able to understand the fundamental genetic basis for its function for over a billion years is really exciting. To have ECU’s name on the research and have us associated with such important marine and coastal biology research is a plus for me.”

 

Photo: ECU researcher John Miller holds a piece of Porphyr umbilicalis, a red alga common in rocky intertidal areas worldwide, on Saturday, July 22, 2017, in West Quoddy Head, Maine. Miller is a primary member of a team that helped map the plant’s genome to study its benefits as a food source.

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