Chloroplast Genomes of Bryophytes

Since the availability of first complete DNA sequence of chloroplast genome of Marchantia polymorpha several studies to determine the structure and organization of chloroplast genomes of various plant groups have been made. However the lineage sampling of bryophytes are poorly represented in complete chloroplast genome sequences (only three liverworts, two mosses and one hornwort). This review presents features of sequenced chloroplast genomes of bryophytes. Introduction Chloroplasts are intracellular organelles present in green plants which contain their own autonomously replicating DNA genome to encode a number of components for the process of photosynthesis (Palmer 1985; Sugiura 1989). Since the availability of first complete DNA sequence of chloroplast genome of Marchantia polymorpha (Ohyama et al. 1986; Ohyama et al. 1988) several studies to determine the structure and organization of chloroplast genomes have been conducted (Nishiyama et al. 2004; Turmel et al. 2006; Jansen et al. 2007). Consequently the nucleotide sequences of many chloroplast genomes which belong to algae, bryophytes, pteridophytes, gymnosperms and angiosperms have been worked out (NCBI Organelle Genome Resources; 248 chloroplast genomes of Viridiplantae as on 08.09.12). Despite of the fact that the first complete chloroplast genome sequenced was of a bryophyte only a small proportion (6 out of 248) of available chloroplast genomes sequenced belong to bryophytes (http://www.ncbi.nlm.nih.gov/genomes/GenomesGroup.cgi?opt=plastid&taxid=33090). Chloroplast genomes are typically represented as circular with an inverted repeat region (containing rRNA and some other genes) dividing the chloroplast genome into large single copy (LSC) and small single copy (SSC) regions. Table 1 presents information of sequenced chloroplast genomes of bryophytes. The present review deals with important features of these chloroplast genomes. Chloroplast Genomes of Liverworts Marchantia polymorpha The first complete chloroplast genome sequence determined belongs to Marchantia polymorpha (Ohyama et al. 1986; Ohyama et al. 1988). The chloroplast DNA of this liverwort contains 121024 base pairs (bp) out of which 20116 bp belongs to large inverted repeats (IRA and IRB, each of 10058 bp) separated by a SSC region of 19813 bp and a LSC region of 81095 bp. Considering the