Additive genes contribute to yield heterosis in rice

The molecular mechanisms underlying heterosis remain unresolved, largely owing to the scarcity of accurately identified heterosis-associated genes. Here, we systematically investigate the inheritance patterns of three yield heterosis-related genes in rice, analyzing their effects in both homozygous and heterozygous genetic backgrounds. We find that heterozygosity at individual loci predominantly produces additive, rather than overdominant, effects in homozygous genetic backgrounds. Nevertheless, heterozygous states of these genes generate yield heterosis in heterozygous genetic backgrounds, supporting the overdominance model. Our findings confirm that heterozygous additive genes are key contributors to yield heterosis in rice.