Identification and physical localization of useful genes and markers to a major gene-rich region on wheat group 1S chromosomes

The short arm of Triticeae homeologous group I chromosomes is known to cont ain many agronomically important genes. The objectives of this study were t o physically localize gene-containing regions of the group 1 short arm, enr ich these regions with markers, and study the distribution of genes and rec ombination. We focused on the major gene-rich region ("1S0.8 region") and i dentified 75 useful genes along with 93 RFLP markers by comparing 35 differ ent maps of Poaceae species. The RFLP markers were tested hy gel blot DNA a nalysis of wheat group 1 nullisomic-tetrasomic lines, ditelosomic lines, an d four single-break deletion lines for chromosome arm 1 Bs. Seventy-three o f the 93 markers mapped to group 1 and detected 91 loci on chromosome 1B. F ifty-one of these markers mapped to two major gene-rich regions physically encompassing 14% of the short arm. Forty-one marker loci mapped to the 1S0. 8 region and 10 to 1S0.5 region. Two cDNA markers mapped in the centromeric region and the remaining 24 loci were on the long arm. About 82% of short arm recombination was observed in the 1S0.8 region and 17% in the 1S0.5 reg ion. Less than 1% recombination was observed for the remaining 85% of the p hysical arm length.