Articles
SOME PROPERTIES OF A STYLAR PROTEIN ASSOCIATED WITH SELF-INCOMPATIBILITY GENOTYPE OF JAPANESE PEAR
The S3-protein (S3-allele associated protein) was subjected to further investigations because of its abundance and clear separation upon isoelectric focusing.
At young bud stages, from 8 to 4 days before flower opening, the S3-protein band was stained lightly but it was strongly stained at 2 days before flower opening or in more advanced stages.
The S3-protein was present only as a soluble from in the mature style of ‘Chojuro’ (S2S3) when the stylar proteins were serially extracted with Tris-HCI buffer, Triton X-100, NaCl, and finally with pectinase-cellulase.
The younger styles of ‘Chojuro’ also contained soluble S3-protein only, suggesting that the S-protein is not bound chemically to cell wall and/or membrane in younger styles but produced gradually in the developing style.
Throughout the style including the stigmatic part, the S3-protein was present, but the concentration was the highest in the upper part of the style.
This distribution pattern was clearly different from that of Nicotiana or Lycopersicon, which possesses the same gametophytic self-incompatibility systems as Japanese pear.
The S3-protein band was separated into several spots when it was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). This means that the S3-protein band may consist of several protein molecules including different glycoforms, alternatively there may be several genes closely linked to S-gene in the style of Japanese pear.