NrDNA internal transcribed spacer revealed molecular diversity in strains of red seaweed Porphyra yezoensis and genetic insights for commercial breeding

Unraveling the cryptic genetic diversity and selective breeding network in various Porphyra strains is of significance for conservation and utilization of economically important nori crops, for both current and future needs. Here, we used nuclear ribosomal spacer (ITS1) region to investigate the genetic variation and intra-specific relatedness of 59 Porphyra yezoensis Ueda specimens worldwide using phylogenetic and parsimony genealogical approaches. 23 nrDNA ITS1 genotypes were revealed and clustering analysis grouped them into two distinct clades. High genetic diversity was detected in wild P. yezoensis strains from Miyagi and Hokkaido Prefectures in Japan, while the cultivated strains from China and South Korea exhibited relatively higher genetic diversity likewise, which provided crucial genetic insights for future commercial breeding of P. yezoensis on a global scale. In addition, phylogenetic study has revealed the genetic relationship of strains with unknown parentage to those with known parentage, and also ITS1 sequence pattern could be correlated with the geographic origin of P. yezoensis specimens. All these pedigree information generated from this research can be used to select parents for inter-specific or intra-specific selective breeding and cross breeding to maximize the preservation of stock resource and sustainable development of nori industry.