A strategy to recover a high-quality, complete plastid sequence from low-coverage whole-genome sequencing1

PREMISE OF THE STUDY We developed a bioinformatic strategy to recover and assemble a chloroplast genome using data derived from low-coverage 454 GS FLX/Roche whole-genome sequencing. METHODS A comparative genomics approach was applied to obtain the complete chloroplast genome from a weedy biotype of rice from Uruguay. We also applied appropriate filters to discriminate reads representing novel DNA transfer events between the chloroplast and nuclear genomes. RESULTS From a set of 295,159 reads (96 Mb data), we assembled the chloroplast genome into two contigs. This weedy rice was classified based on 23 polymorphic regions identified by comparison with reference chloroplast genomes. We detected recent and past events of genetic material transfer between the chloroplast and nuclear genomes and estimated their occurrence frequency. DISCUSSION We obtained a high-quality complete chloroplast genome sequence from low-coverage sequencing data. Intergenome DNA transfer appears to be more frequent than previously thought.