Gene Complements of Lactuca sativa and its Wild Progenitor Lactuca serriola

The whole genome of Lactuca sativa cv. Salinas has been sequenced in collaboration with the BGI and a consortium of ten breeding companies (http://lgr.genomecenter.ucdavis.edu/). To understand the evolutionary events underlying lettuce domestication, we have initiated a comparative analysis of L. sativa with its closest wild relative and likely progenitor L. serriola. We sequenced gene space libraries of L. sativa and L. serriola and compared coverage of predicted gene models using the lettuce genome assembly. Gene space reads from a large RIL population of a L. sativa x L. serriola cross were used to confirm the differences in genome representation in these two Lactuca species. In addition, RNA-Seq libraries from both species were used to assist in the analysis. Using CLC Genomics Workbench we analyzed coverage for single copy genes and multi-gene families with a particular emphasis on disease resistance genes. Both highly conserved and diverged (fast evolving?) sequences were identified. Comparative studies on the complete L. sativa and L. serriola genomes is ongoing. Ultimately, this will lead to understanding of the genome architecture of transcribed sequences, the organization and evolution of gene families, as well as the role of repetitive and transposable elements in Lactuca species.