Genome characterization of a breeding line derived from a cross between Oryza sativa and Oryza rufipogon

A preliminary screening was conducted on BC3F1 and BC4F1 backcross families developed from crossing Oryza sativa (MR219) and O. rufipogon (IRGC105491). Despite earlier results showing that O. rufipogon alleles (wild introgression) contributed to both number of panicles (qPPL-2) and tillers (qTPL-2) at loci RM250, RM208, and RM48 in line A20 of the BC2F2 population, we observed that wild introgression was lost at loci RM250 and RM208 but retained at locus RM48 in BC3F1 and BC4F1. Progeny tests conducted utilizing genotype and phenotype data on both BC4F1 and a reference population, BC2F7 (A20 line), did not show significant differences between groups having the MR219 allele and wild introgression at locus RM48. This suggests that there is no additive and transgressive effect of wild introgression in the BC3F1 and BC4F1 generated. The presence of wild introgression was largely due to gene contamination by cross-pollination during field breeding practices.