Fig. 5

Epistatic Interactions Contributing to the Heterosis of PH and EW. a Proportions of additive, dominant, and epistatic QTLs detected by GWAS for the three traits. The number of QTLs for each trait were averaged over the thirty F₁ populations. b Different contributions of additive (Add), dominant (Dom), and epistatic (Epi) effects to DTT, PH, and EW. We computed the cumulative QTL effects for the three classes of QTLs based on the significant QTLs detected in each of the thirty F₁ populations. c An epistatic interaction between the BR2 and ubi3 QTLs contributes to the heterotic performance of PH in F₁ hybrids. In the maternal population (left panel), the ubi3-AA genotype exhibited the shortest PH in the BR2-aa background (green boxes), indicating that BR2-aa suppresses ubi3-AA. In the Zheng58 (BR2-TT and ubi3-tt in Zheng58) F₁ population (middle panel), the ubi3-tA genotype exhibited the tallest PH in the BR2-Ta background (green boxes), indicating that the suppression of ubi3 by BR2 is relieved due to the complementation of the recessive BR2-t allele by the dominant BR2-T allele in F₁ hybrids. The superior heterotic performance is also reflected in the MPH of PH (right panel). Uppercase bases represent dominant alleles and lowercase bases represent recessive alleles. d Epistatic interaction between BR2 and ubi3 QTLs contributes to the heterotic performance of EW in F₁ hybrids