Positional cloning of the rice Rf-1 gene, a restorer of BT-type cytoplasmic male sterility that encodes a mitochondria-targeting PPR protein

Theor Appl Genet. 2004 May;108(8):1449-57. doi: 10.1007/s00122-004-1591-2. Epub 2004 Feb 14.

Abstract

The combination of cytoplasmic male sterility (CMS) in one parent and a restorer gene ( Rf) to restore fertility in another are indispensable for the development of hybrid varieties. We have found a rice Rf-1 gene that restores BT-type CMS by applying a positional cloning strategy. Using linkage analysis in combination with 6,104 BC(1)F(3) progeny derived from a cross between two near-isogenic lines (NILs) differing only at the Rf-1 locus, we delimited the Rf-1 gene to a 22.4-kb region in the rice genome. Duplicate open reading frames ( Rf-1A and Rf-1B) with a pentatricopeptide (PPR) motif were found in this region. Since several insertions and/or deletions were found in the regions corresponding to both the Rf-1A and Rf-1B genes in the maintainer's allele, they may have lost their function. Rf-1A protein had a mitochondria-targeting signal, whereas Rf-1B did not. The Rf-1B gene encoded a shorter polypeptide that was determined by a premature stop codon. Based on the function of the Rf-1 gene, its product is expected to target mitochondria and may process the transcript from an atp6/orf79 region in the mitochondrial genome. Since the Rf-1A gene encodes a 791-amino acid protein with a signal targeting mitochondria and has 16 repeats of the PPR motif, we concluded that Rf-1A is the Rf-1 gene. Nine duplications of Rf-1A homologs were found around the Rf-1 locus in the Nipponbare genome. However, while some of them encoded proteins with the PPR motif, they do not restore BT-type CMS based on the lack of co-segregation with the restoration phenotype. These duplicates may have played diversified roles in RNA processing and/or recombination in mitochondria during the co-evolution of these genes and the mitochondrial genome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Chromosome Mapping*
  • Chromosomes, Plant / genetics
  • Cloning, Molecular
  • Cytoplasm / genetics*
  • Evolution, Molecular
  • Fertility / genetics
  • Genes, Duplicate / genetics
  • Genes, Plant / genetics*
  • Genome, Plant
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Molecular Sequence Data
  • Oryza / genetics*
  • Phenotype
  • Plant Proteins / chemistry
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism*
  • Protein Transport
  • Sequence Analysis, DNA

Substances

  • Plant Proteins

Associated data

  • GENBANK/AB112808
  • GENBANK/AB112809
  • GENBANK/AB112810
  • GENBANK/AB112811