Abstract
Genetic analyses of controlled crosses in wheat have identified a region on chromosome 3B (short arm) that controls variation in water stress tolerance. The region, near the Sr2 resistance locus, is covered by a series of well studied BAC clones that are being sequenced as part of a large 3B sequencing program in France (led by Catherine Feuillet, INRA, and the International Wheat Genome Sequencing Consortium). A 1Mb region from this part of the wheat genome (ctg506) was assembled based on sequence data from overlapping BAC clones. The sequencing of the BAC clones combined standard Sanger sequencing (5-8 x coverage) and Solexa/Illumina short read sequencing. Annotation of the sequence identified the IVR1 gene considered to be important in conferring drought and frost tolerance to wheat when the stress occurs early in head development. Alignment to the rice and Brachypodium genome sequences indicated very little synteny and detailed analyses provided a sequence based model accounting for the evolutionary instability in this region of the genome.