Complete nucleotide sequence of the sugarcane (Saccharum officinarum) chloroplast genome: a comparative analysis of four monocot chloroplast genomes.

The complete nucleotide sequence of the chloroplast genome of sugarcane (Saccharum officinarum) has been determined. It is a circular double-stranded DNA molecule, 141,182 bp in size, and is composed of a large single copy of 83,048 bp, a small single copy of 12,544 bp, and a pair of inverted repeat regions of 22,795 bp each. A comparative analysis among monocots showed that the sugarcane chloroplast genome was very similar to maize but not to rice or wheat. Between sugarcane and maize at the rps16-trnQ (UUG) region, however, a length polymorphism was identified. With regard to insertions/deletions equal to or longer than 5 bp, a total of 53 insertion and 31 deletion events were identified in the sugarcane chloroplast genome. Of the 84 loci identified, a pair of direct repeat sequences was located side by side in a tandem fashion in 47 loci (56.0%). A recombination event during plant evolution is discussed at two sites between the sugarcane and tobacco chloroplast genomes.