Scientists crack genome of superfood seaweed
Along the tropical coastline of Okinawa, Japan, farmers raise rows of delectable seaweed and harvest thousands of tons of the crop each year. Unfortunately, scientists predict that pollution and rising ocean temperatures will blunt this impressive yield, forcing farmers to adopt new cultivation techniques. Recently, scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) decoded the genome of the popular brown seaweed ito-mozuku (Nemacystus decipiens), providing data that could someday be critical to local farmers.
The study, published in Scientific Reports, presents the world’s first draft genome of ito-mozuku. Just three years ago, the unit released the first draft genome of another local species of edible seaweed, Cladosiphon okamuranus, called Okinawa mozuku. Both seaweed species contain exceptionally high concentrations of fucoidan, a slimy substance thought to stymie the formation of blood clots and cancerous tumors, among other health benefits. The researchers have spotted which genes drive up this fucoidan concentration, a discovery that could have applications in the health food industry.
“My future plan is to establish new methods for cultivation of this species,” said Dr. Koki Nishitsuji, first author of the study and a staff scientist in the OIST Marine Genomics Unit, led by Prof. Noriyuki Satoh. Nishitsuji is now working to develop genetic markers to distinguish ito-mozuku from its close cousin.
Compared to other brown seaweeds, such as kombu (Saccharina japonica) or wakame (Undaria pinnatifida), both ito-mozuku and Okinawa mozuku are incredibly rich sources of fucoidan. The reason why might be coded in their genes.
The researchers found that both mozuku species contain a fused gene that drives their fucoidan production. On their own, the two genes code for two separate enzymes–proteins that facilitate chemical reactions and ultimately help produce fucoidan. Once fused, the genes can be expressed simulataneously and produce a single enzyme equipped with two functions. Armed with a double-edged enzyme, mozuku likely pumps out fucoidan in a fraction of the time it takes other seaweeds, Nishitsuji said.