cDNA cloning and molecular analysis of two self-incompatibility alleles from apple

Plant Mol Biol. 1995 Feb;27(3):499-511. doi: 10.1007/BF00019317.


Complementary DNA clones representing two alleles of the self-incompatibility (S) locus of apple (Malus x domestica Borkh.) have been isolated and characterised. One of the alleles corresponds to a 29 kDa ribonuclease (S-RNase) that was purified from pistil tissue. On northern blots, both cDNAs hybridized to a transcript that was only present in pistils and not in the other plant tissues analysed. Corresponding genomic sequences, amplified by PCR, were found to contain a single intron of 138 bp and 1100 bp respectively. Comparison of both sequences shows that the cDNAs encode mature proteins containing 65% of identical residues. Eight invariable cysteine residues, conserved regions around two histidines thought to play a role in RNA catalysis, and a number of other distinct residues are conserved between the apple S-RNases and similar proteins in the family Solanaceae. As this is the first report of sequences of S-alleles from a species belonging to a family that is not related with the Solanaceae, the structural features of S-RNases deduced from a comparison of their sequences are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles*
  • Amino Acid Sequence
  • Base Sequence
  • Cloning, Molecular
  • Conserved Sequence / genetics
  • DNA, Complementary / genetics*
  • DNA, Plant / genetics*
  • Fruit / enzymology
  • Fruit / genetics*
  • Fruit / physiology
  • Genes, Plant / genetics
  • Introns / genetics
  • Molecular Sequence Data
  • Ribonucleases / genetics
  • Ribonucleases / isolation & purification
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • DNA, Complementary
  • DNA, Plant
  • Ribonucleases

Associated data

  • GENBANK/U12199
  • GENBANK/U12200