Extracts from styles, developed at different temperatures, and their effect on compatibility of Petunia hybrida in excised-style culture

The growth of Petunia clone W166K. (S| S2; self-incompatible) pollen tubes in Brewbaker & Kwack’s medium is inhibited by extracts from clone T2U (S3S3; also self-incompatible) styles. The styles were collected one day before anthesis from plants grown either at a day/night temperature regime of 25.5/18°C (extracts A) or 19.5°/18°C (extracts B). High molecular (protein) extracts B had a much stronger effect than high molecular extracts A. After enzymatic breakdown of the proteins the inhibition by extract A was as strong as that by extract B. From these results it is concluded that prior to anthesis pollen tube growth stimulating proteins are being synthesized in the style when the day temperature is sufficiently high. The inhibitory effects of the low molecular weight carbohydrate extracts A and B were the same.