Pollen Tube Growth Inhibitors Involved in the Ovary of Self-Incompatible Japanese Pear

摘要

The growth inhibitors of pollen tubes in the pistils of Japanese pear‘Chojuro’were studied in vitro to elucidate the physiological mechanism of self-incompatibility.Addition of water extracts from ovaries into a well dug in an agar medium containing sucrose and boric acid inhibited the growth of incompatible pollen tubes more strongly than that of compatible ones. The substance, tentatively called Sinhibitor (self-inhibitor), was detectable in a relatively wide range of concentrations of the extract, from 10- to 60-fold dilution. However, it was absent in the stylar extract.S-inhibitor was stable, even though the extract was heated to 100°C for 10 min. The chromatogram of the S-inhibitor following a Sephadex G-10 gel filtration showed 2 peaks of inhibition: one peak corresponded to the peaks of protein and phenol (phenols may be conjugated with proteins), and the other to that of reducing sugar.The water extract from mature ovaries when diluted 10-fold was a stronger growth inhibitor of incompatible pollen tubes compared with that from immature ones. This substance, tentatively called A-inhibitor (adult-inhibitor), appeared to be different from S-inhib