Mapping the Rust Resistant Loci MXC3 and MER in P. trichocarpa and Assessing the Intermarker Linkage Disequilibrium in MXC3 Region
- ORNL
- West Virginia University
In an attempt to elucidate the molecular mechanisms of Melampsora rust resistance in Populus trichocarpa, we have mapped two resistance loci, MXC3 and MER, and intensively characterized the flanking genomic sequence for the MXC3 locus and the level of linkage disequilibrium (LD) in natural populations. We used an interspecific backcross pedigree and a genetic map that was highly saturated with AFLP and SSR markers, and assembled shotgun-sequence data in the region containing markers linked to MXC3. The two loci were mapped to different linkage groups. Linkage disequilibrium for MXC3 was confined to two closely linked regions spanning 34 and 16 kb, respectively. The MXC3 region also contained six disease-resistance candidate genes. The MER and MXC3 loci are clearly distinct, and may have different mechanisms of resistance, as different classes of putative resistance genes were present near each locus. The suppressed recombination previously observed in the MXC3 region was possibly caused by extensive hemizygous rearrangements confined to the original parent tree. The relatively low observed LD may facilitate association studies using candidate genes for rust resistance, but will probably inhibit marker-aided selection.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 936838
- Journal Information:
- New Phytologist, Vol. 764, Issue 1; ISSN 0028-646X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Pseudovitamin D deficient rickets (PDDR). Linkage disequilibrium mapping in young populations
Anonymous marker loci within 400 kb of HLA-A generate haplotypes in linkage disequilibrium with the hemochromatosis gene (HFE)