The power of selection: Dissecting phenotypic plasticity and linkage drag underlying yield traits of rice (Oryza sativa) using selective introgression

The power of selection and phenotypic plasticity of seven rice grain yield (GY) traits was dissected using DNA markers and 226 Minghui86 introgression lines (ILs) phenotyped across four contrast environments of long-day versus short-day and drought versus irrigated conditions. Linkage mapping identified 77 main-effect quantitative trait loci (QTLs) plus 15 groups of epistatic QTLs affecting the GY traits. By characterizing genomic introgression patterns of the donor alleles in ILs selected for high- and low-trait values based on replicated progeny testing across each of the four environments and for high- and low-GY across nine different environmental scenarios, 246 QTLs affecting the seven yield traits were identified. Genetic drag from tight repulsive linkage of genes with opposite effects on the same traits was detected in 45 cases involving 90 (35.8%) QTLs, indicating its wide presence in superior Chinese hybrid parents. The demonstrated selective introgression strategy, including the developed ILs plus the genetic information on the associations of introgressed donor alleles with the yield traits in the ILs would provide a useful platform for future breeding by design.