Primary structural features of rosaceous S-RNases associated with gametophytic self-incompatibility

Plant Mol Biol. 1998 Aug;37(6):931-41. doi: 10.1023/a:1006078500664.


We isolated cDNA clones encoding five S-RNases (S1-, S3-, S5-, S6-, S7-RNases) from pistils of Pyrus pyrifolia (Japanese pear), a member of the Rosaceae. Their amino acid sequences were aligned with those of other rosaceous S-RNases sequenced so far. A total of 76 conserved amino acid residues were stretched throughout the sequence, but were absent from the 51-66 region which was designated the hypervariable (HV) region. The phylogenetic tree of rosaceous S-RNases showed that S-RNase polymorphism predated the divergence of Pyrus and Malus. Pairwise comparison of these S-RNases detected two highly homologous pairs, P. pyrifolia S1- and S4-RNases (90.0%) and P. pyrifolia S3- and S5-RNases (95.5%). The positions of amino acid substitutions between S1- and S4-RNases were spread over the entire region, but in the pair of S3- and S5-RNases, amino acid substitutions were found in the 21-90 region including the HV region. The substitutions in this restricted region appear to be sufficient to discriminate between S3 and S5 pollen and to trigger the self-incompatible reaction.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Base Sequence
  • Cloning, Molecular
  • Crosses, Genetic
  • DNA, Complementary / genetics
  • Evolution, Molecular
  • Fertility / genetics
  • Fruit / enzymology
  • Fruit / genetics*
  • Haploidy
  • Molecular Sequence Data
  • Ribonucleases / genetics*
  • Rosales / enzymology
  • Rosales / genetics*
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Species Specificity


  • DNA, Complementary
  • Ribonucleases
  • ribonuclease S

Associated data

  • GENBANK/AB002139
  • GENBANK/AB002140
  • GENBANK/AB002141
  • GENBANK/AB002142
  • GENBANK/AB002143