The First Plant Genome

quences. The map also gave a very precise estimate of possible especially in problem areas that could be tackled early in the project. The efficacy of this approach is shown in Figure 1. The use of BAC fingerprinting at a genome-wide scale was hence first demonstrated with The sequence of the model plant Arabidopsis thaliana the Arabidopsis project and created the paradigm by was published last year. A. thaliana is an annual crucifer-which the human genome was successfully mapped and ous weed, related to mustards and cabbages, and its 5 sequenced (McPherson et al., 2001). chromosomes and 125 Mb genome have been the object Selected BACs were sequenced using shotgun se-of genetic and molecular studies for more than 50 years. quencing. Over the course of the project, various nu-Given its central role in plant genetics, and as the first ances of this procedure were used and a targeted accu-representative of the plant kingdom to be sequenced, racy of one error per 10,000 bases was met or far the Arabidopsis genome was eagerly anticipated by exceeded in most cases (Arabidopsis Genome Initiative, plant biologists and evolutionary biologists alike. Com-2000). The higher order contiguity of the sequence, de-parison with animal and microbial genomes, as well as rived in large part from the quality of the " up-front " the implications for plant biology, are reviewed here. mapping, is also very significant. Three of the 5 chromo-First, though, we consider the sequencing strategy cho-somes are contiguous from telomere repeats to centro-sen for Arabidopsis, as well as its outcome.Getting There bout et al., 2000) while the remaining two chromosomes The Arabidopsis genome sequencing project began in have fewer than 10 gaps each between telomeric and 1995-1996, during a transitional period in genome se-centromeric repeat structures (Theologis et al., 2000; quence analysis. The eventual success of a clone-by-Tabata et al., 2000). In addition, substantial amounts clone approach to sequencing a complex genome was (roughly half) of the pericentromeric and other hetero-evident by this time based on the C. elegans sequencing chromatin have been sequenced and linked to the ge-project. More simple microbial genomes had been com-netic map (Copenhaver et al., 1999; Arabidopsis Ge-pleted using a whole genome shotgun approach. While nome Initiative, 2000; CSHL/WUGSC/PEB Arabidopsis a whole genome shotgun strategy was considered for Sequencing Consortium, 2000). An additional 20–30 Arabidopsis, it was abandoned early in the planning BAC contigs which are linked to the centromeric …