Mapping resistance to the bird cherry-oat aphid and the greenbug in wheat using sequence-based genotyping

Area of Science:

• Plant Genetics and Breeding
• Agricultural Entomology
• Molecular Genetics

Background:

• Wheat aphids, including Rhopalosiphum padi (bird cherry-oat aphid) and Schizaphis graminum (greenbug), are significant pests of common wheat (Triticum aestivum L.).
• Understanding the genetic basis of aphid resistance is critical for developing resistant wheat cultivars and mitigating crop losses.

Purpose of the Study:

• To identify and map quantitative trait loci (QTL) associated with resistance to R. padi and S. graminum in wheat.
• To characterize the genetic architecture of aphid resistance in wheat, including potential interactions between resistance loci.

Main Methods:

• Phenotypic evaluation of 140 recombinant inbred lines (RILs) derived from a cross between susceptible (Seri M82) and resistant (CWI76364) wheat lines for R. padi antibiosis and tolerance, and S. graminum resistance.
• Greenhouse and field-based phenotyping for aphid infestation and plant damage.
• Sequence-based genotyping to identify marker-trait associations and map resistance QTL.

Main Results:

• A novel QTL for R. padi antibiosis (QRp.slu.4BL) was identified on chromosome 4BL, explaining 10.2% of phenotypic variation.
• Two QTLs for R. padi tolerance (QRp.slu.5AL and QRp.slu.5BL) were detected on chromosomes 5AL and 5BL, with evidence of epistatic interaction involving a locus on 3AL.
• A new QTL for S. graminum resistance (QGb.slu-2DL) was mapped to chromosome 2DL, and a previously reported gene (putatively Gba) was re-mapped to 7DL.

Conclusions:

• Novel QTLs conferring resistance to R. padi and S. graminum have been identified in wheat, providing valuable genetic resources for breeding programs.
• This study reports the first QTL for R. padi resistance in wheat and the first association of chromosome 2DL with S. graminum resistance.
• The identified resistance QTLs have potential for introgression into elite wheat cultivars to enhance aphid pest management strategies.