title: cDNA cloning and molecular analysis of two self-incompatibility alleles from apple.
abstract: 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.
authors.affiliation: F.A. Janssens Laboratory of Genetics, Katholieke Universiteit Leuven, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Broothaerts
authors.forename: G A
authors.initials: GA
authors.lastname: Janssens
authors.forename: P
authors.initials: P
authors.lastname: Proost
authors.forename: W F
authors.initials: WF
authors.lastname: Broekaert
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics*; D005638:Fruit / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D017343:Genes, Plant / Q000235:genetics; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D012260:Ribonucleases / Q000235:genetics / Q000302:isolation & purification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D012260:Ribonucleases