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Abstract

Arabidopsis thaliana was the first plant, and the third multicellular organism after Caenorhabditis elegans and Drosophila melanogaster to have a reference strain completely sequenced. In order to leverage the extensive genomic information available for A. thaliana, including an increasing amount of knowledge of within-species diversity, as well as to better understand plant genome evolution in general, we proposed two close relatives for genome sequencing (Arabidopsis lyrata and Capsella rubella). A. lyrata is the closest well-characterized relative in the same genus as A. thaliana, and Capsella is the closest well-characterized genus. Both genomes are being ~8-fold shotgun sequenced. An assembly for A. lyrata is being finalized, while sequencing of Capsella rubella is in progress. Comparing the genomes of A. thaliana, A. lyrata, and C. rubella provides an unprecedented opportunity to understand key aspects of plant genome evolution in species that share high enough sequence identity that intermediate genomic changes can be directly determined. In detail, assignment of ancestral states for Arabidopsis using C. rubella as outgroup; genome-wide analysis of microstructural evolution in plants; elucidation of genome size variation in closely related species; functional information from these species will likely be directly transferable to other relevant plant species, certainly to the many heavy-metal accumulators in the same family (e.g., Arabidopsis halleri), which are of interest for bioremediation; much of functional information from these species will also apply to the fairly closely related poplar, of interest for carbon sequestration and energy production, and already sequenced by the JGI.