SRA

Among four species of genus Hydra of phylum Cnidaria, H. viridissima and H. vulgaris show stable endosymbiotic associations with green algae. It has been suggested that symbiosis between H. viridissima and the algae occurred once in ancestral viridissima group and has been maintained thereafter. In contrast, in H. vulgaris, only two strains so far examined (J7 and J10) harbor green algae. However, it is not known whether those strains obtained the algae before the divergence of those strains or independently of each other. In order to understand the origin and evolution of symbiosis of H. vulgaris, we first constructed the phylogenetic trees of (1) the symbiotic algae using 18SrRNA gene, and (2) H. vulgaris strains using mitochondrial genome. Next, we introduced the algae into non-symbiotic H. vulgaris group strains that are maintained in National Institute of Genetics, Japan.