bims-plasge Biomed News
on Plastid genes
Issue of 2024‒09‒29
two papers selected by
Vera S. Bogdanova, Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences
  1. Identification and variation of a new restorer of fertility gene that induces cleavage in orf138 mRNA of Ogura male sterility in radish.
  2. Mitochondrial phylogeny and distribution of cytoplasmic male sterility-associated genes in Beta vulgaris.
  1. Theor Appl Genet. 2024 Sep 25. 137(10): 231
    Identification and variation of a new restorer of fertility gene that induces cleavage in orf138 mRNA of Ogura male sterility in radish.
    Hiroshi Yamagishi, Ayako Hashimoto, Asumi Fukunaga, Mizuki Takenaka, Toru Terachi.
      KEY MESSAGE: 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.
    DOI:  https://doi.org/10.1007/s00122-024-04736-4
  2. PLoS One. 2024 ;19(9): e0308551
    Mitochondrial phylogeny and distribution of cytoplasmic male sterility-associated genes in Beta vulgaris.
    Keishi Kubota, Mion Oishi, Eigo Taniguchi, Akiho Akazawa, Katsunori Matsui, Kazuyoshi Kitazaki, Atsushi Toyoda, Hidehiro Toh, Hiroaki Matsuhira, Yosuke Kuroda, Tomohiko Kubo.
      Cytoplasmic male sterility (CMS) is a mitochondrial-encoded trait that confers reproductive defects in males but not in females or any vegetative function. Why CMS is so often found in plants should be investigated from the viewpoint of mitochondrial phylogeny. Beta vulgaris, including the wild subspecies maritima and cultivated subspecies vulgaris (e.g., sugar beet), is known to be mitochondrially polymorphic, from which multiple CMS mitochondria have been found, but their evolutionary relationship has been obscure. We first refined the B. vulgaris reference mitochondrial genome to conduct a more accurate phylogenetic study. We identified mitochondrial single-nucleotide polymorphic sites from 600 B. vulgaris accessions. Principal component analysis, hierarchical clustering analysis, and creation of a phylogenetic tree consistently suggested that B. vulgaris mitochondria can be classified into several groups whose geographical distribution tends to be biased toward either the Atlantic or Mediterranean coasts. We examined the distribution of CMS-associated mitochondrial genes from Owen, E- and G-type CMS mitochondria. About one-third of cultivated beets had Owen-type CMS, which reflects the prevalence of using Owen-type CMS in hybrid breeding. Occurrence frequencies for each of the three CMS genes in wild beet were less than 4%. CMS genes were tightly associated with specific mitochondrial groups that are phylogenetically distinct, suggesting their independent origin. However, homologous sequences of the Owen type CMS gene occurred in several different mitochondrial groups, for which an intricate explanation is necessary. Whereas the origin of cultivated beet had been presumed to be Greece, we found an absence of Owen-type mitochondria in Greek accessions.
    DOI:  https://doi.org/10.1371/journal.pone.0308551
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