A Killer-Protector System Regulates Both Hybrid Sterility and Segregation Distortion in Rice

Conquering Rice Sterility The hybrid sterility occurring among rice species has long been a puzzle and hampers progress in breeding crops with improved performance and yield characteristics. Yang et al. (p. 1336 ) have identified three linked genes encoding a killer, a partner, and a protector protein. The killer and partner work together to kill female gametes not carrying the functional protector, resulting in preferential transmission of gametes carrying the functional protector, which also causes segregation distortion in the progeny. This explanation for how reproductive isolation is maintained among species of rice, and perhaps other organisms, also offers approaches for boosting yields by intersubspecific heterosis.