Duplication and Loss of Function of Genes Encoding RNA Polymerase III Subunit C4 Causes Hybrid Incompatibility in Rice.

Reproductive barriers are commonly observed in both animals and plants, in which they maintain species integrity and contribute to speciation. This report shows that a combination of loss-of-function alleles at two duplicated loci, () on chromosome 4 and on chromosome 7, causes pollen sterility in hybrid progeny derived from an interspecific cross between cultivated rice, , and an Asian annual wild rice, Male gametes carrying the allele from ( ) and the allele from ( ) were sterile, but female gametes carrying the same genotype were fertile. We isolated the causal gene, which encodes a protein homologous to DNA-dependent RNA polymerase (RNAP) III subunit C4 (RPC4).