Along the tropical coastline of Okinawa, Japan, farmers plant a series of delicious seaweeds every year and harvest thousands of tons of crops. Unfortunately, scientists predict that pollution and rising ocean temperatures will weaken this impressive output and force farmers to adopt new cultivation techniques. Recently, scientists at the Okinawa Graduate School of Science and Technology (OIST) have decoded the genome of the popular brown seaweed too-mozuku ( Nemacystus decipiens ), providing data that may one day be of vital importance to local farmers.
The study was published on March 14, 2019 in the scientific report which introduced the genome sketch of the world's first ito-mozuku. Just three years ago, the department released the first genome sketch of another locally edible seaweed variety, Cladosiphon okamuranus called Okinawa mozuku. Both seaweeds contain very high concentrations of fucoidan, a viscous substance believed to prevent the formation of blood clots and cancerous tumors, as well as other health benefits. Researchers have discovered which genes have pushed up this fucoidan concentration, a finding that could be used in the health food industry.
In addition to revealing genes that make mozuku a health benefit, the study may be useful for agriculture.
"My future plan is to create new ways to nurture this species," said Dr. Nishitsuji, the lead author of the study and a scientist at the OIST Marine Genomics Department, led by Professor Noriyuki Satoh. Nishitsuji is working hard to develop genetic markers to distinguish ito-mozuku and its close relatives.
"With these markers, we can carry out cross breeding," he said. “This is a popular method of making new varieties of terrestrial plants, especially wheat and potatoes, but in the case of seaweed, no one has successfully carried out crossbreeding.”
The Marine Genomics Department conducted their research with the help of Onna Fisheries Cooperative, which is located on the corner of the OIST campus. The team established the “Onna-1” strain of ito-mozuku in 2006 and provided samples for genome research. The stock plans to continue sequencing the samples of the cooperative, but one day they hope to further expand their research.
"So far, we plan to continue our ' seaweed project in Okinawa," Nishitsuji said. "If possible, we hope to expand it to cover the whole of Japan."
Compared to other brown algae, such as kelp ( Saccharina japonica ) or wakame ( wakame ' ), ito-mozuku and Okinawa mozuku are very rich Source of fucoidan. They may be encoded in their genes.
The researchers found that both mozuku species contain a fusion gene that drives their fucoidan production. The two genes themselves are the codes of two different enzymes – proteins that promote chemical reactions that ultimately contribute to the production of fucoidan. Once fused, the gene can simultaneously express and produce a single enzyme with two functions. Nishitsuji said that with the double-edged enzyme, mozuku may extract fucoidan from a small portion of the other algae.
The researchers found another pair of fusion genes in ito-mozuku that were not found in Okinawa mozuku. They predict that when expressed, these genes may increase the amount of sulfate groups transferred to fucoidan, a chemical reaction that may be critical to the health of the substance. The unit plans to test the theory in future research as they continue to collect genomic data from brown seaweeds in Okinawa and Japan.
"Land crops have a long history of genetic research," Nishitsuji said. “But no one has done this research in algae.” The Marine Genomics Department understands the cultural and economic importance of the crop in Japan and aims to accelerate our understanding of algae.
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