title: Additive and over-dominant effects resulting from epistatic loci are the primary genetic basis of heterosis in rice.
abstract: A set of 148 F9 recombinant inbred lines (RILs) was developed from the cross of an indica cultivar 93-11 and japonica cultivar DT713, showing strong F1 heterosis. Subsequently, two backcross F1 (BCF1) populations were constructed by backcrossing these 148 RILs to two parents, 93-11 and DT713. These three related populations (281BCF1 lines, 148 RILs) were phenotyped for six yield-related traits in two locations. Significant inbreeding depression was detected in the population of RILS and a high level of heterosis was observed in the two BCF1 populations. A total of 42 main-effect quantitative trait loci (M-QTLs) and 109 epistatic effect QTL pairs (E-QTLs) were detected in the three related populations using the mixed model approach. By comparing the genetic effects of these QTLs detected in the RILs, BCF1 performance and mid-parental heterosis (HMP), we found that, in both BCF1 populations, the QTLs detected could be classified into two predominant types: additive and over-dominant loci, which indicated that the additive and over-dominant effect were more important than complete or partially dominance for M-QTLs and E-QTLs. Further, we found that the E-QTLs detected collectively explained a larger portion of the total phenotypic variation than the M-QTLs in both RILs and BCF1 populations. All of these results suggest that additive and over-dominance resulting from epistatic loci might be the primary genetic basis of heterosis in rice.
authors: Department of Plant Genetics and Breeding and State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China.
authors: Xiaojin
authors: X
authors: Luo
authors: Yongcai
authors: Y
authors: Fu
authors: Peijiang
authors: P
authors: Zhang
authors: Shuang
authors: S
authors: Wu
authors: Feng
authors: F
authors: Tian
authors: Jiayong
authors: J
authors: Liu
authors: Zuofeng
authors: Z
authors: Zhu
authors: Jinshui
authors: J
authors: Yang
authors: Chuanqing
authors: C
authors: Sun
mesh_terms: D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004843:Epistasis, Genetic; D005799:Genes, Dominant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D006823:Hybrid Vigor / Q000235:genetics*; D007178:Inbreeding; D012275:Oryza / Q000235:genetics*; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D011995:Recombination, Genetic / Q000235:genetics