show Abstracthide AbstractThe origin and early diversification of flowering plants (angiosperms) had profound impacts on Earth's biota, providing the raw genetic material from which most crops and economically important plants were derived. The diversification of genes, genomes, and important traits cannot be adequately interpreted without a comparative evolutionary framework firmly rooted with genome sequences from basal angiosperms. As the sister species to all other extant flowering plants, Amborella trichopoda holds a singular position in the flowering plant tree of life for establishing this comparative genomics framework. Toward this goal, we have sequenced, assembled, and annotated the nuclear genome sequence of Amborella trichopoda using a combination of multi-platform whole genome shotgun sequencing, Fluorescent In Situ Hybridization (FISH), and genome-wide optical mapping. We also sequenced 12 additional individuals sampled from wild populations representing the native range of Amborella on New Caledonia. The Amborella Genome Sequencing Project is a collaborative NSF-funded project that seeks to produce a high-quality finished genome sequence that will serve as a reference in comparative evolutionary analyses to shed light on the genomic characteristics of the last common ancestor of extant flowering plants. Data are publicly available through the Amborella Genome Database, hosted at http://amborella.org.