Unveiling Transcriptional and Translational Regulators Driving Heterosis in Leafy Vegetable with Cytoplasmic Male Sterility

Heterosis and cytoplasmic male sterility (CMS) are fundamental to modern plant hybrid breeding, yet the molecular basis governing biomass heterosis and the influence of CMS on hybrid vigor remain elusive. In this study, we integrated transcriptome and translatome profiling to dissect these mechanisms in Brassica rapa ssp. chinensis (bok choy), comparing two F1 hybrids, derived from crosses with a CMS line or its maintainer line, with their three parent lines. While both hybrids exhibited significant leaf biomass heterosis, this effect was attenuated in the CMS-derived hybrid. Transcriptome analysis uncovered key developmental regulators with non-additive gene expression. Ribosome profiling further revealed non-additive translational efficiency (TE) in hybrids associated with biomass vigor. Notably, CMS was found to interrupt both allele-specific GE and allele-specific TE in hybrids, suggesting mitochondrial-nuclear interactions modulate heterotic outcomes. Taken together, these findings provide novel insights into both transcriptional and translational control that underlie biomass heterosis in plant CMS-based breeding.