Chloroplast and mitochondrial genomes from a liverwort, Marchantia polymorpha--gene organization and molecular...

The complete nucleotide sequence of chloroplast DNA (121,025 basepairs, bp) from a liverwort, Marchantia polymorpha, has made clear the entire gene organization of the chloroplast genome. Quite a few genes encoding components of photosynthesis and protein synthesis machinery have been identified by comparative computer analysis. We also identified the complete nucleotide sequence of the liverwort mitochondrial DNA and deduced 96 possible genes in the sequence of 186,608 bp. The complete nucleotide sequence from chloroplast DNA comprises twenty introns (19 group II and 1 group I) in 18 different genes. One of the chloroplast group II introns separated the ribosomal protein gene in the trans-position. The mitochondrial genome also has thirty-two introns (25 group II and 7 group I) in the coding regions of 17 genes. From the evolutionary point of view, we describe the origin of organellar introns which gave the evidence for their vertical and horizontal transfers and their intragenic propagation, and RNA editing which was apparently lacking in the liverwort chloroplast and mitochondrial genomes.