Mapping and validating stem rust resistance genes directly in self-incompatible genetic resources of winter rye

Area of Science:

• Plant genetics
• Agricultural science
• Crop improvement

Background:

• Rye (Secale cereale L.) genetic resources are naturally diverse and cross-pollinating.
• Traditional linkage mapping for disease resistance requires extensive inbreeding, which is time-consuming.

Purpose of the Study:

• To demonstrate the direct mapping of stem rust resistance genes within diverse rye populations.
• To provide an efficient alternative to traditional inbreeding-based mapping.

Main Methods:

• Testing diverse rye populations for stem rust resistance using a leaf-segment assay with three rust isolates.
• Genotyping 74 plants per population using a 10K-SNP chip.
• Analyzing associations between infection scores and marker alleles with cumulative logit models.

Main Results:

• Identified three significant loci (Pgs1, Pgs2, Pgs3) associated with stem rust resistance in three distinct populations.
• Validated resistance-linked markers through independent field experiments.
• Successfully fixed two populations for resistance using validated markers.

Conclusions:

• Monogenically inherited seedling resistance genes can be directly mapped in genetic resources.
• This approach offers a competitive alternative to laborious, multi-generational inbreeding for linkage mapping.
• Facilitates faster breeding for stem rust resistance in rye.