Advances and perspectives in crop heterosis

Heterosis, or hybrid vigor, refers to the phenomenon that F1 hybrids show superior performance over their parents on traits like yield, adaptation, etc. This common phenomenon in plants has gained a wide range of applications in hybrid breeding. Although heterosis has been proposed and utilized for more than a century, the molecular network and underlying mechanism of it remain unclear. There are three major hypotheses which explain the genetic basis of heterosis: dominance complementation, over-dominance and epistasis. The identification of heterotic loci and the elucidation of the gene network and epigenetic regulation lead to a better understanding of heterosis. With the fast growth of multiple omics, genome editing, big data analytics and machine learning, the research on heterosis may gain substantial progress in future. Here we review the recent advances in heterosis and aim to shed light on future research. We also provide potential solutions to overcome the bottlenecks in heterosis research and application, as well as the strategies of hybrid breeding in China in the short, medium, and long term.