Porphyra – the economic seaweed as a new experimental system

Marine algae, popularly known as sea-weeds, are sources of food, fodder, ferti-lizer, medicine and chemicals1. Worldtrade in seaweed and its products was val-uedat US $50million in 1970, US $250million in 1990 and US $6.2billion in1999 (refs 1 and 2). About 20,000 marinealgae species are distributed throughoutthe world, out of which only 221 speciesare utilized commercially. These include145 species for food and 110 species forphycocolloid production1.Porphyra(Ban-giales,Rhodophyta) popularly known as‘Nori’ in Japan, ‘Kim’ in Korea and ‘Zicai’in China has an annual value of over US$1.8billion3.Porphyrais primarily usedas food, wrapped around the Japanesedelicacy ‘Sushi’ whichconsists of roas-ted blades, raw fish, rice and other ingre-dients. The alga is not only delicious butalso contains high levels of protein (25–50%), vitamins (higher vitamin C than inoranges), trace minerals and dietary fibres4.The plant contains nearly17 types offree amino acids, including taurine whichcontrols blood cholesterol levels5. Thealga is a preferred source of the red pig-mentr-phycoerythrin, which is utilizedas a fluorescent ‘tag’ in the medical diag-nostic industry6.Porphyrahas been cul-tivated for the past hundred years in Japanand today it is one of the largest aquacul-ture industries in Japan, Korea andChina6. Because of its economic impor-tance and other health benefits,Porphyracultivation is now being expanded toother countries7. Recently, it has beenfound that the plant has much more poten-tial and can be used as an experimentalsystem likeArabidopsis thalianain thehigher plants, some aspects of which arediscussed here.