Biological pathway expression complementation contributes to biomass heterosis in Arabidopsis

Heterosis, referring to the better performance of an F1 hybrid compared with its parents, has been greatly exploited in agriculture to improve yield. Nevertheless, our understanding of its genetic and molecular mechanism has remained limited. We investigated the temporally dynamic phenotypes and transcriptomes during early seedling development in two Arabidopsis ecotypes together with their hybrid and unveiled differences in the transcriptional regulatory network between the hybrid and parents, orchestrating the hybrid growth vigor. Moreover, we found complementary high-parent expression in the hybrid between the network hub genes involved in photosynthesis and cell cycle. Our findings provide molecular-level evidence that dominant expression complementation between genes involved in two fundamental biological pathways contributes to heterosis.