An efficient method for measuring copy number variation applied to improvement of nematode resistance in soybean.
Copy number variation (CNV) is implicated in important traits in multiple crop plants, but can be challenging to genotype using conventional methods. The Rhg1 locus of soybean, which confers resistance to soybean cyst nematode (SCN), is a CNV of multiple 31.2-kb genomic units each containing four genes. Reliable, high-throughput methods to quantify Rhg1 and other CNVs for selective breeding were developed. The CNV genotyping assay described here uses a homeologous gene copy within the paleopolyploid soybean genome to provide the internal control for a single-tube TaqMan copy number assay. Using this assay, CNV in breeding populations can be tracked with high precision. We also show that extensive CNV exists within Fayette, a released, inbred SCN-resistant soybean cultivar with a high copy number at Rhg1 derived from a single donor parent. Copy number at Rhg1 is therefore unstable within a released variety over a relatively small number of generations. Using this assay to select for individuals with altered copy number, plants were obtained with both increased copy number and increased SCN resistance relative to control plants. Thus, CNV genotyping technologies can be used as a new type of marker-assisted selection to select for desirable traits in breeding populations, and to control for undesirable variation within cultivars.
Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Tong Geon
TG
Lee
Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Brian W
BW
Diers
Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. mhudson@illinois.edu.
Matthew E
ME
Hudson
D056915:DNA Copy Number Variations / Q000235:genetics*; D060467:Disease Resistance / Q000235:genetics; D005838:Genotype; D010935:Plant Diseases / Q000235:genetics* / Q000469:parasitology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000235:genetics* / Q000469:parasitology*
D010940:Plant Proteins

Rhg1
; copy number variation; marker-assisted selection; polyploids; soybean; technical advance