Abstract
The primitive unicellular red alga Cyanidium caldarium, as well as Cyanidioschyzon merolae, grows in acidic and high temperature conditions around hot springs. Cyanidium caldarium RK-1 was found in Japan and well studied by Japanese researchers. This strain differs from another strain RK-1 used by the group of Germany, because their plastid genome sequence are different. The phylogenetic analyses of some plastid genes indicate that Japanese C. caldarium RK-1 is more closely related to C. merolae rather than German C. caldarium RK-1. Furthermore, we found that Japanese C. caldarium RK-1 is much more closely related to Galdieria maxma rather than C. merolae. The plastid genome is known to be a circular DNA of about 150 kbp and we have already analyzed ~75% of it. Although many of the plastid genes of Japanese C. caldarium RK-1 have very high similarity to those of C. merolae, we found differences in several gene orders.
