Expression analysis of genes encoding PPR proteins on both alleles of the Rfo locus. RT-PCR were carried out on total RNA from radish flower buds using primers specific for each gene and electrophoresed on a 1% agarose gel. Lanes O: negative PCR control (no substrate); lanes RT-: control without reverse transcriptase on DNAse treated RNA before amplification; lanes RT+: RT-PCR reaction; lanes G: PCR amplification from genomic DNA; lanes M: molecular size standards (GeneRuler 1 kb DNA ladder, Fermentas). A. The primers used were PPRA:20505U22 and PPRA:20954L21, which amplify PPR-A in D81Rfo and PPR-2 in L7rfo. B. The primers used were Rfocons1047U22 and PPRB:13225L22, which amplify PPR-B in D81Rfo. C. The primers used were PPR1:21229U22 and PPR1:21229U22, which amplify PPR-1 L7rfo.