Unraveling novel mechanisms controlling heterosis in seeds: advances and biotechnological applications in crops.

Heterosis refers to the superior performance of hybrids over their parents (inbred lines) in one or more characteristics. Hence, understanding this process is crucial for addressing food insecurity. This review explores the traditional genetic models proposed to explain heterosis and integrates them with emerging perspectives such as epigenetic studies and multi-omics approaches, which are increasingly used to investigate the molecular basis of heterosis in plants. We focus especially on the role of heterosis on seed quality traits in different plant species, considering seed development as one of the most important steps in the plant life cycle. We examine how heterosis enhances plant establishment, growth and seed yield in hybrids compared with their parental lines. We also review the involvement of this process in tolerance and resistance against environmental stresses such as drought, salinity, and heat. While this review primarily focuses on seed biology impact of heterosis, we also discuss recent studies highlighting the role of heterosis in other key factors, such as the rhizosphere microbiome. Finally, we consider the use of recent technologies to broaden the spectrum of crops suitable for hybrid breeding.