Structural variation hotspots in the soybean genome localize to clusters of biotic stress response genes

Genome-wide structural and gene content variation were assessed among four diverse soybean cultivars using both hybridization and resequencing approaches. Many chromosomes exhibited relatively low rates of structural variation, however several copy number variation hotspots were observed in specific regions, most prominently on chromosomes 3, 6, 7, 16 and 18. Structural variation hotspots localized to gene-rich regions that were enriched for clustered multi-gene families. The most abundant gene families associated with these hotspots were the Nucleotide Binding (NB) and Receptor-Like Protein (RLP) classes, which are important for plant biotic defense responses. Implications for these findings are discussed.