Genomic and epigenetic insights into the molecular bases of heterosis

Key Points Century-old genetic models are limited in their ability to explain the molecular bases of heterosis. Transcriptomic, proteomic, metabolic and epigenomic studies provide new insights into parental genomic interactions, leading to regulatory and network changes and heterosis. Genetic and epigenetic reprogramming of individual genes, regulatory factors and their associated networks in hybrids promotes growth, stress tolerance and fitness. Key regulators can be manipulated using biochemical and transgenic approaches to alter biological networks and heterosis. Although heterosis is most extensively studied in plants, the principles uncovered in plants are likely to apply more broadly across organisms. Heterosis, also known as hybrid vigour, is an intriguing phenomenon that has particularly important implications for agriculture. The molecular basis of this vigour is poorly understood, but progress is being made through the use of genomic, transcriptomic and epigenomic approaches. Heterosis, also known as hybrid vigour, is widespread in plants and animals, but the molecular bases for this phenomenon remain elusive. Recent studies in hybrids and allopolyploids using transcriptomic, proteomic, metabolomic, epigenomic and systems biology approaches have provided new insights. Emerging genomic and epigenetic perspectives suggest that heterosis arises from allelic interactions between parental genomes, leading to altered programming of genes that promote the growth, stress tolerance and fitness of hybrids. For example, epigenetic modifications of key regulatory genes in hybrids and allopolyploids can alter complex regulatory networks of physiology and metabolism, thus modulating biomass and leading to heterosis. The conceptual advances could help to improve plant and animal productivity through the manipulation of heterosis.