Studying Stem Rust and Leaf Rust Resistances of Self-Fertile Rye Breeding Populations

Area of Science:

• Plant Pathology
• Agronomy
• Genetics

Background:

• Stem rust (SR) and leaf rust (LR) are major diseases affecting cultivated rye in Central Europe, leading to significant yield losses.
• Developing resistant rye cultivars is essential for sustainable agriculture and food security.
• Pyramiding monogenic and race-nonspecific resistances is a key strategy for durable disease control.

Purpose of the Study:

• To identify and map quantitative trait loci (QTLs) for resistance to SR and LR in cultivated rye.
• To validate known resistance genes and discover novel loci conferring resistance.
• To inform breeding programs for developing rye varieties with enhanced disease resistance.

Main Methods:

• Screening of six breeding populations and one testcross population for SR and LR resistance in multi-environmental field trials.
• Genotyping of populations using a 10K SNP marker chip and DArTseqTM.
• Utilizing seedling tests to differentiate between adult-plant and all-stage resistance for SR.

Main Results:

• Ten SR-QTLs were identified, reducing stem coverage by 5-17%. Four mapped to known SR QTL positions.
• The gene *Pgs3.1* on chromosome 2R, conferring 40% SR infection reduction, was validated.
• Two large-effect LR loci (*Pr7* and *Pr8*) on chromosomes 1R and 2R were mapped, reducing leaf area by 34% and 21%, respectively. An additional 9% LR reduction QTL was found on chromosome 1R.

Conclusions:

• This study successfully identified several novel QTLs and validated a known gene for SR and LR resistance in rye.
• The discovered resistance loci provide valuable genetic resources for breeding programs aiming to improve rye's disease resistance.
• The findings contribute to developing more resilient rye cultivars, crucial for mitigating yield losses due to rust diseases.