Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kita-ku, Kyoto, Kamigamo, 603-8555, Japan.
Center for Plant Sciences, Kyoto Sangyo University, Motoyama, Kita-ku, Kyoto, Kamigamo, 603-8555, Japan.
Theor Appl Genet. 2024 Sep 25;137(10):231. doi: 10.1007/s00122-024-04736-4.
A new restorer of fertility gene, Rfs, of Ogura cytoplasmic male sterility (CMS) in radish encodes a pentatricopeptide repeat protein that binds to 15 nucleotides in mRNA of the CMS gene, orf138. Nucleotide substitutions in both Rfs and orf138 determine effectiveness and specificity of restoration. Cytoplasmic male sterility (CMS) in plants caused by the expression of abnormal mitochondrial genes results from impaired pollen production. The manifestation of CMS is suppressed by the restorer of fertility (Rf) genes in the nuclear genome. Thus, the CMS-Rf system is a suitable model for studying the direct interactions of mitochondrial and nuclear genes. At least nine haplotypes, of which Type B is ancestry, have been reported for the Ogura CMS gene, orf138, in radish (Raphanus sativus). We previously observed that Rfo encoding a pentatricopeptide repeat (PPR) protein, ORF687, which inhibits the translation of orf138 is ineffective in one haplotype (i.e., Type H). Here, we carried out map-based cloning of another Rf gene (Rfs) that cleaves the orf138 mRNA of Type H. Rfs produces a PPR protein consisting of 15 PPR motifs that binds to the mRNA, cleaving the mRNA at about 50nt downstream of the binding site. However, Rfs was ineffective for Type A because of a single nucleotide substitution in the binding site. Both Rfo and Rfs suppress orf138 expression in ancestral Type B, but they are rendered ineffective in Type H and Type A, respectively, by a single nucleotide substitution in orf138.
萝卜 Ogura 细胞质雄性不育（CMS）的新育性恢复基因 Rfs 编码一种五肽重复蛋白，该蛋白与 CMS 基因 orf138 的 mRNA 中的 15 个核苷酸结合。Rfs 和 orf138 中的核苷酸替换决定了恢复的有效性和特异性。植物 CMS 是由于异常线粒体基因的表达导致花粉生产受损而引起的。CMS 的表现受到核基因组中育性恢复（Rf）基因的抑制。因此，CMS-Rf 系统是研究线粒体和核基因直接相互作用的合适模型。至少有 9 种单倍型已在萝卜（Raphanus sativus）的 Ogura CMS 基因 orf138 中被报道，其中 B 型是祖先型。我们之前观察到，编码五肽重复（PPR）蛋白 Rfo 的orf138 抑制翻译的 Rfo 在一种单倍型（即 H 型）中无效。在这里，我们对另一个 Rf 基因（Rfs）进行了基于图谱的克隆，该基因可以切割 H 型的 orf138 mRNA。Rfs 产生由 15 个 PPR 基序组成的 PPR 蛋白，该蛋白与 mRNA 结合，在结合位点下游约 50nt 处切割 mRNA。然而，由于结合位点的单个核苷酸替换，Rfs 对 A 型无效。Rfo 和 Rfs 均能抑制祖先型 B 中的 orf138 表达，但由于 orf138 中的单个核苷酸替换，它们在 H 型和 A 型中分别失效。
