STYLE-SPECIFIC AND DEVELOPMENTALLY-REGULATED ACCUMULATION OF A GLYCOSYLATED THAUMATIN PR5-LIKE PROTEIN IN JAPANESE PEAR (PYRUS-SEROTINA REHD.)/

The stylar proteins of Japanese pear (Pyrus serotina Rehd.) were analy zed by two-dimensional gel electrophoresis, and a 32-kDa protein with an isoelectric point of 4.8 was found to be a major component in the s tyle. The 32-kDa protein was a soluble glycoprotein which reacted with concanavalin A. The 32-kDa protein specifically accumulated in the st yle in a developmentally regulated manner, but was not detected in the other floral organs and leaves. An oligonucleotide representing the N -terminal amino acid sequence of the 32-kDa protein was used to amplif y a cDNA fragment by polymerase chain reaction (PCR). The generated PC R product was used to screen a style cDNA library. The selected cDNA c lone encoded 244 amino acid residues containing the N-terminal sequenc e of the 32-kDa protein. The N-terminus of the protein was preceded by putative signal peptide of 22 amino acid residues. The 32-kDa protein showed significant homology with the thaumatin/PR5-like proteins, and was named PsTL1 (Pyrus serotina thaumatin-like protein 1). The possib le biological role of PsTL1 in the styles is discussed.