Analysis of Self-incompatibility Reaction in Easter Lily by Using Heat Treatments

Abstract

Abstract Self-incompatibility of Easter lily (Lilium longiflorum Thunb.) was overcome by heating the styles. Immersing detached prepollinated styles in distilled water at 45C for 5 min promoted the growth of incompatible pollen tubes. When heat-treated styles were kept at 25C for various periods before pollination, the effect of overcoming selfincompatibility diminished as the period between the heat treatment and pollination was increased. Heat treatment of styles within 2 hr after incompatible pollination promoted the growth of pollen tubes to a distance comparable to compatible ones. When the styles were heated during the period from 3 to 8 hr after incompatible pollination, the growth of pollen tubes was retarded to some extent as compared to those treated within 2 hr after pollination. Treatment at 12 or more hours after pollination no longer promoted the growth of incompatible pollen tubes. These results suggest that overcoming self-incompatibility by heating is temporary and the incompatibility machinery is already induced at ≈3 hr after pollination.