Enabling marker-assisted breeding in pea

Yu Ma

Marker-assisted breeding (MAB), which involves the use of DNA markers to more efficiently predict trait performance is now widely used in crop breeding. Pea, the plant used by Gregor Mendel to illuminate the principle of genetics, lags behind other more economically important crops in terms of available molecular genomics and genetics resources, hindering the application of MAB. This study focuses on enhancing our understanding of economically important traits associated with stringlessness, high levels of mineral nutrients and powdery mildew resistance in pea by identifying trait-associated loci and/or predictive DNA markers to enable efficient and precise MAB. For the stringless pod phenotype, two sequence characterized amplified region (SCAR) markers with a predictive accuracy of 85% were identified through targeted region and amplification technology (TRAP). For the seed mineral study, using a genotyping by sequencing approach, genome-wide single nucleotide polymorphism (SNP) markers and a high-density linkage map were established for seed mineral concentration and content, as well as 100-seed weight. Forty six seed mineral concentration quantitative trait loci (QTLs) and thirty seven seed mineral content QTLs for boron, calcium, iron, potassium, magnesium, manganese, molybdenum, phosphorous, sulfur, and zinc, and six 100-seed weight QTLs were identified. The QTLs explained from 2.4% to 43.3% of the phenotypic variance. Comparative maps between pea and closely related legumes showed syntenic regions that can be utilized for identifying candidate markers and beneficial alleles to improve mineral nutrient levels. For powdery mildew resistance, four breeder-friendly kompetitive allele specific PCR (KASPar) markers were developed. The genotyping results of the four markers were validated on a pea core collection, exactly matching the genotyping results from the corresponding functional markers. One pea germplasm accession potentially carrying a new powdery mildew resistance allele was successfully detected. Overall, the trait-associated DNA markers developed in this study have potential for use in MAB to enable improvement of selection efficiency in pea breeding programs.

Enabling marker-assisted breeding in pea

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