A tripartite genetic conflict system controls hybrid sterility in rice.

Abstract

Interspecific Asian-African hybrid rice could substantially boost yield but is limited by severe hybrid sterility. We identify <i>RHS3</i> as a major quantitative trait locus controlling this trait. <i>RHS3</i> encodes a tripartite toxin-antidote system composed of MAO, DUN, and JIA, in which MAO acts as a toxin that aborts gametes by disrupting mitochondrial function, whereas DUN and JIA function as antidotes that neutralize MAO toxicity, conferring a transmission advantage to the African allele. We demonstrate that detoxification relies on selective autophagy through formation of a tripartite JIA-DUN-MAO protein complex. We infer the de novo origin of <i>RHS3</i> in the AA-genome rice lineage, illustrating a role for genetic conflict in speciation and suggesting strategies to harness heterosis between Asian and African rice.