Genetic diversity of Kappaphycus Doty and Eucheuma J. Agardh (Solieriaceae, Rhodophyta) in Southeast Asia

The commercial importance of carrageenophytes Kappaphycus and Eucheuma is well known, with much interest in terms of cultivation, marketing, and research. Considering the many lucrative prospects, these red seaweeds were introduced into various parts of the world for farming, where merely a few were comprehensively documented. Despite being extensively cultivated throughout Southeast Asia, the genetic diversity of Kappaphycus and Eucheuma is poorly studied, where heavy reliance is placed on the use of local or commercial names for identifications. This study used the mitochondrial-encoded cox1 and cox2-3 spacer genetic markers to investigate the Kappaphycus and Eucheuma haplotypes, cultivated and wild, available throughout Southeast Asia. Concatenated cox1-cox2-3 spacer datasets were also analyzed. The near full-length cox1 gene is preferred at revealing the genetic diversity of Kappaphycus and Eucheuma, provided a larger reference database is available. Both molecular markers were capable of delineating common members of the genus Kappaphycus (i.e., Kappaphycus alvarezii, Kappaphycus striatus, and Kappaphycus cottonii) and Eucheuma denticulatum, and revealed interesting genotypes and new species which may be potential alternatives to the common cultivars as well as materials for research. The relative scarcity of Eucheuma species is discussed and future sites for sampling are recommended.