Plant Molecular Biology

, Volume 37, Issue 6, pp 931–941

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

  • Takeshi Ishimizu
  • Toyohide Shinkawa
  • Fumio Sakiyama
  • Shigemi Norioka
Article

DOI: 10.1023/A:1006078500664

Cite this article as:
Ishimizu, T., Shinkawa, T., Sakiyama, F. et al. Plant Mol Biol (1998) 37: 931. doi:10.1023/A:1006078500664

Abstract

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.

amino acid sequencingcDNARosaceaeS-allele specificityself-incompatibilityS-RNase

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Takeshi Ishimizu
    • 1
  • Toyohide Shinkawa
    • 1
  • Fumio Sakiyama
    • 1
  • Shigemi Norioka
    • 1
  1. 1.Division of Protein Chemistry, Institute for Protein ResearchOsaka UniversitySuita, OsakaJapan