Abstract
The primitive unicellular red alga Cyanidium caldarium, as well as Cyanidioschyzon merolae, grows in acidic and high temperature conditions around hot springs. Almost all nucleotide sequence of the plastid genome of Cyanidium caldarium RK-1 was determined. The plastid genome is AT-rich circular DNA of about 150 kbp. The plastid genome contains more genes for ribosomal proteins and photosynthesis components than that in green plant. Moreover, it possess genes that are involved in the synthesis of amino acids, fatty acids, and pigments. Although many of the plastid genes of C. caldarium RK-1 are high similar to those of C. merolae, Some genes and gene order are different.
