A set of introgression lines (ILs) containing chromosomal segments from O. rufipogon (IRGC 105491), a wild relative of O. sativa, in the genetic background of an elite U.S. variety, cv. Jefferson, was developed to confirm the performance of six yield-enhancing quantitative trait loci (QTLs). Fifty BC3F3 ILs containing homozygous O. rufipogon introgressions across each of the target QTL regions, and as few background introgressions as possible, were selected for evaluation of yield and 14 yield-related traits in field studies conducted over two years at four locations in the southern U.S. Performance of the IL families was compared with three commercial inbreds and one hybrid variety. IL families carrying introgressions from the low-yielding wild parent at the QTLs, yld2.1 and yld6, yielded 27.7% and 26.1% more than Jefferson. IL yld2A also performed well under alternate wetting and drying conditions in two field locations, and had greater levels of resistance to four diseases. After the first year of field trials, 10 of the top-performing BC3F4 families, representing five of the QTL targets, were genotyped with an Illumina 1,536 assay to define the size and location of the wild introgressions. BC3F4 families with the fewest background introgressions were backcrossed to Jefferson and selfed. The resulting BC4F2 families were screened with targeted SNP assays to identify individuals carrying homozygous introgressions across the target QTLs. Twelve ILs, representing each of the six QTL targets, are available for studies on transgressive variation and as interspecific pre-breeding lines.
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