The S11 and S13 self incompatibility alleles in Solanum chacoense Bitt. are remarkably similar.
A genomic clone of the S11 allele from the self-incompatibility locus (S locus) in Solanum chacoense Bitt. has been isolated by cross-hybridization to the S. chacoense S13 allele and sequenced. The sequence of the S11 allele contains all the features expected for S genes of the Solanaceae, and S11 expression, as assessed by northern blots and RNA-PCR, was similar to that of other S. chacoense S alleles. The S11 protein sequence shares 95% identity with the phenotypically distinct S13 protein of S. chacoense and is the gametophytic S allele with the highest similarity to an existing allele so far discovered. Only 10 amino acid changes differentiate the mature proteins from these two alleles, which sets a new lower limit to the number of changes that can produce an altered S allele specificity. The amino acid substitutions are not clustered, suggesting that an accumulation of random point mutations can generate S allele diversity. The S11 intron is unusual in that it could be translated in frame with the coding sequence, thus suggesting an additional mechanism for the generation of new S alleles.
Saba-el-Leil
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MK
Institut de Recherche en Biologie Végétale, Montréal, Québec, Canada.
Rivard
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S
Morse
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Cappadocia
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D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D018076:DNA, Complementary; D017343:Genes, Plant / Q000235:genetics*; D015698:Genomic Library; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000235:genetics*
D018076:DNA, Complementary; D010940:Plant Proteins; C086762:S11 protein, Solanum chacoense; C086763:S13 protein, Solanum chacoense