Identification and characterization of stylar glycoproteins associated with self-incompatibility genes of Japanese pear, Pyrus serotina Rehd.
Japanese pear (Pyrus serotina Rehd.) exhibits gametophytic self-incompatibility. Following our previous findings that basic ribonucleases in the styles of Japanese pear are associated with self-incompatibility genes (S-RNases), stylar proteins with high pI values were analyzed by two-dimensional gel electrophoresis further to characterize S-RNases. A group of basic proteins of about 30 kDa associated with self-incompatibility genes were identified. These proteins contained sugar chains which reacted with concanavalin A and wheat germ agglutinin, and thus were designated as S-glycoproteins of Japanese pear. The fact that the S-glycoprotein was expressed at a much lower level in a self-compatible mutant than in the original variety suggested a role of S-glycoproteins in mediating self-incompatibility of Japanese pear. Immunoblot analysis indicated that S-glycoproteins are identical to previously identified S-RNases. The S-glycoproteins were predominantly expressed in the style, in the ovary in trace amounts, and not in leaf, pollen or germinated pollen. The N-terminal amino acid sequences of the S-glycoproteins showed homology not only with each other but also with those of the S-allele-associated proteins from plants of the family Solanaceae at levels of about 30-50%.
Sassa
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Faculty of Horticulture, Chiba University, Japan.
Hirano
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Ikehashi
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D000483:Alleles; D000595:Amino Acid Sequence; D015153:Blotting, Western; D005638:Fruit / Q000235:genetics*; D006023:Glycoproteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D007106:Immune Sera; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014197:Trees / Q000235:genetics
D006023:Glycoproteins; D007106:Immune Sera; D010940:Plant Proteins; D012260:Ribonucleases