title: Structural and transcriptional analysis of the self-incompatibility locus of almond: identification of a pollen-expressed F-box gene with haplotype-specific polymorphism.
abstract: Gametophytic self-incompatibility in Rosaceae, Solanaceae, and Scrophulariaceae is controlled by the S locus, which consists of an S-RNase gene and an unidentified "pollen S" gene. An approximately 70-kb segment of the S locus of the rosaceous species almond, the S haplotype-specific region containing the S-RNase gene, was sequenced completely. This region was found to contain two pollen-expressed F-box genes that are likely candidates for pollen S genes. One of them, named SFB (S haplotype-specific F-box protein), was expressed specifically in pollen and showed a high level of S haplotype-specific sequence polymorphism, comparable to that of the S-RNases. The other is unlikely to determine the S specificity of pollen because it showed little allelic sequence polymorphism and was expressed also in pistil. Three other S haplotypes were cloned, and the pollen-expressed genes were physically mapped. In all four cases, SFBs were linked physically to the S-RNase genes and were located at the S haplotype-specific region, where recombination is believed to be suppressed, suggesting that the two genes are inherited as a unit. These features are consistent with the hypothesis that SFB is the pollen S gene. This hypothesis predicts the involvement of the ubiquitin/26S proteasome proteolytic pathway in the RNase-based gametophytic self-incompatibility system.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ushijima
authors.forename: Hidenori
authors.initials: H
authors.lastname: Sassa
authors.forename: Abhaya M
authors.initials: AM
authors.lastname: Dandekar
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gradziel
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Tao
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hirano
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D005298:Fertility / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D006239:Haplotypes / Q000235:genetics* / Q000502:physiology; D008025:Ligases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011058:Pollen / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D027861:Prunus / Q000235:genetics* / Q000378:metabolism; D012260:Ribonucleases / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D014157:Transcription Factors; D044767:Ubiquitin-Protein Ligases; D012260:Ribonucleases; D008025:Ligases