Due to the capacity to deliver favorable target traits to offspring via breeder selection,backbone parents carrying accumulated favor-able agronomic traits have been used widely in breeding programs in crop species,such as rice,wheat,cotton,and maize (Zhou et al.,2016;Fradgley et al.,2019;Li et al.,2019;Ma et al.,2019;Han et al.,2020).It is estimated that 3656 (～70％) of the major Chinese rice varieties released from the year 1950-2008 were found to be derived from as few as 35 backbone parents (Tang et al.,2012).Large-scale genome sequencing of diverse rice accessions has been emerged as a promising technology for the identification of key genomic regions or loci under selection during rice domestica-tion (Huang et al.,2012;Wang et al.,2018) and genetic improvement(Xie et al.,2015).On the other hand,sequence information derived from breeding pedigrees could also help to unravel how favorable genomic regions were transmitted from parents to their offspring,as demonstrated by the researches on the pedigrees of the well-known rice varieties Minghui 63 and Huanghuazhan (Zhou et al.,2016;Chen et al.,2017;Huang et al.,2018).These researches enhanced the understanding of the cumulative effects of beneficial alleles at limited loci in selected offspring varieties.A few examples include IPA1,Gn1a,GW5,GS3,and GS5 for high grain yield,Waxy for good grain eating quality,and Xa21 for high adversity adaptability.However,little is known on how the genomic architecture containing multiple gene loci is passed from backbone parents to offspring in rice breeding.