Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Comparative DNA Sequencing Of The Medicago truncatula, Cicer arietenum And Sorghum bicolor Chloroplast Genomes

Graham B. Wiley , Majesta Siegried , Shaoping Lin , Ying Fu , Fares Najar , Bruce A Roe

  Department of Chemistry and Biochemistry Stephenson Research and Technology Center The University of Oklahoma 101 David L. Boren Blvd. Norman, Oklahoma 73019

The chloroplast, an organelle responsible for the photosynthetic reactions in plants, contains a unique genome encoding many of the genes necessary for this process (1). The chloroplast genomes of land plants are relatively well conserved both at the level of gene content as well as the gene order (2). Any divergence that has occurred between chloroplast genomes is generally unique meaning that if two genomes have the same gene content and order, it is often as a result of shared ancestry (2). To shed additional light on the evolutionary processes occurring in the chloroplast genome, we have sequenced three chloroplast genomes, two from the dicot legumes, Medicago truncatula (AC093544) and Cicer arietenum (AC145820) and one from the monocot cereal Sorghum bicolor (AC144549). The comparison of the Sorghum chloroplast to those of the two legumes provides information on evolutionary changes that have occurred in the chloroplast genome over a relatively large period of time, since monocots and dicots diverged ~200 mya (3). A direct comparison of the two legume chloroplast genomes reveals the evolutionary changes that occurred over a relatively short period of time, since the two legumes diverged ~25 mya (4). The extent of these changes and their possible implications in chloroplast function will be presented.
(1) T. Kato, T. Kaneko, S. Sato, Y. Nakamura, and S. Tabata. Complete structure of the chloroplast genome of a legume, Lotus japonicus. DNA Research 7: 323-330 (2000).
(2) K. Kim and H. Lee. Widespread occurrences of small inversions in the chloroplast genomes of land plants. Mol. Cell 19(1): 104-113 (2004).
(3) M. Sanderson, J. Thorne, N. Wikstrom, and K. Bremer. Molecular evidence on plant divergence times. American Journal of Botany 91(10): 1656-1665 (2004).
(4) H. Choi, J. Mun, D. Kim, H. Zhu, J Baek, J. Mudge, B. Roe, N. Ellis, J. Doyle, G. Kiss, N. Young, and D. Cook. Estimating genome conservation between crop and model legume species. PNAS 101(43): 15289-15294 (2004).