Morphological and genetic differentiation of cultivated Undaria pinnatifida (Laminariales, Phaeophyta)

摘要

Abstract To clarify the significance of genetic resources in the marine crop Undaria pinnatifida, we investigated whether morphological features of two cultivars were genetically different from each other based on combined studies of morphological and molecular analyses. The two cultivars were produced, respectively, by self-fertilization between male and female gametophytes, which were each developed from a single zoospore from two morphologically different sporophytes cultivated in the eastern Seto Inland Sea, Japan. Their sporophytes, each with the same genotype, were cultivated in an Undaria farm under the same environmental conditions and were periodically collected for morphometric comparisons. The results of this experimental cultivation demonstrate that various morphological features, such as the blade, stipe, and sporophyll shapes, and developmental processes of the divided blade and sporophyll, clearly differed between the two cultivars. Although the two cultivars showed identical haplotypes in both of the mitochondrial cox3 gene and the tatC-tLeu region, they exhibited different genotypes at the microsatellite loci. These results indicate that morphological and developmental differences were genetically controlled, in addition to phenotypic plasticity due to changes in environmental conditions. It is therefore necessary for the marine crop breeding program to collect more mature sporophytes of cultivated and wild U. pinnatifida from various regions and to establish more female and male gametophyte strains each developed from a single zoospore. The origin of U. pinnatifida cultivated in the eastern Seto Inland Sea, famous for Japanese Undaria cultivation, is also discussed.]]>