Molecular and physiological basis of heterosis in hybrid rice performance

Heterosis is often exploited to produce high-yielding crops with better performance than their inbred counterparts. Commercial rice breeding has made use of this phenomenon as well, primarily through the use of cytoplasmic male sterility (CMS) and environment-sensitive genic male sterility (EGMS). However, a limited understanding of the molecular and physiological basis of heterosis prevents researchers from harnessing the full potential of hybrid breeding. This review examines the various explanations and mechanisms of heterosis in rice, including evidence fitting the established theories of heterosis and the use of modern omics approaches to characterizing heterosis and heterosis-related traits. Overdominance was the most frequently cited mechanism behind yield-related traits and various molecular and physiological markers associated with heterosis were identified.