Non-functional allele of the RF2 fertility restorer of rice varieties with LD-type cytoplasmic male sterility (CMS) (PubMed:21265890). Non-functional RF2 alleles are found in japonica cultivars Taichung 65 and Nipponbare (AC F1SZ44), and is due to the presence of THR-78 which replaces ILE-78 in the functional allele (PubMed:21265890). Functional allele is found in the japonica cultivars Fukuyama and Owarihatamochi (AC F1SZ42), and indica cultivar Kasalath (AC F1SZ41) (PubMed:21265890). Specifically expressed during anther development, from the uninucleate pollen stage to the tricellular pollen stage, with the highest expression at the tricellular pollen stage.