A complete BAC-based physical map of the Arabidopsis thaliana genome

Arabidopsis thaliana is a small flowering plant that serves as the major mo del system in plant molecular genetics'. The efforts of many scientists hav e produced genetic maps that provide extensive coverage of the genome (http ://genome-www.stanford.edulArabidopsis/maps.html). Recently, detailed YAC, BAG, P1 and cosmid-based physical maps (that is, representations of genomic regions as sets of overlapping clones of corresponding libraries) have bee n established that extend over wide genomic areas ranging from several hund reds of kilobases(2,3) to entire chromosome(4-9). These maps provide an ent ry to gain deeper insight into the A. thaliana genome structure. A. thalian a has been chosen as the subject of the first large-scale project intended to determine the full genome sequence of a plant(10). This sequencing proje ct, together with the increasing interest in map-based gene cloning, has hi ghlighted the requirement for a complete and accurate physical map of this plant species. To supply the scientific community with a high-quality resou rce, we present here a complete physical map of A. thaliana using essential ly the IGF BAC library(11) The map consists of 27 contigs that cover the en tire genome, except for the presumptive centromeric regions, nucleolar orga nization regions (NOR) and telomeric areas. This is the first reported map of a complex organism based entirely on BAC clones and it represents the mo st homogeneous and complete physical map established to date for any plant genome. Furthermore, the analysis performed here serves as a model for an e fficient physical mapping procedure using BAC clones that can be applied to other complex genomes.