Study on substances regulating pollen germination in Japanese chestnut

本研究旨在阐明板栗花柱花粉萌发和花粉管生长的调控物质。（Et Zucc.）与胚珠发育有关。柱头上的花粉萌发和花粉管生长在花柱停止生长后开始，尽管雄花已经开始开花。花柱生长初期用水提取液对花粉萌发和花粉管生长有明显的抑制作用，但随着花柱停止生长，其抑制作用逐渐消失。提取液的HPLC分析表明，从保留时间判断，抑制物质可能为莽草酸。花柱生长初期和柱头花粉萌发及花粉管生长初期，提取液中糖含量均较高。当花粉管开始在柱头上生长时，胚珠发育处于早期阶段，子房中每个胚珠都不形成珠心。不同分析条件下提取液的HPLC分析表明，柱头花粉萌发和花粉管开始生长前后花柱产生的抑制物质和促进物质可能同时存在。然而，这些物质的产生与胚珠的发育之间没有明显的关系。因此，柱头上的花粉萌发和花粉管生长受柱头和花柱本身产生的物质调控。

The study was conducted to clarify the substances regulating pollen germination and pollen tube growth in the styles of Japanese chestnut (Castanea crenata Sieb. Et Zucc.) in concerned with development of ovules. Pollen germination and pollen tube growth on the stigma began after the style ceased to grow, although the anthesis of male flowers had already began. The solution extracted with water from the styles at early stage of the growth repressed remarkably pollen germination and pollen tube growth, although its repressive effect disappeared as the style ceased the growth. The HPLC analysis of the extracted solution showed that repressive substance might be shikimic acid, as estimated from retention time. Sugar content in the extracted solution was higher both at early stage of the style growth and at the beginning of pollen germination and pollen tube growth on the stigma. When pollen tubes began to grow on the stigma, the development of ovules was at early stage in which no nucellus was formed in each ovules in a ovary. The HPLC analysis of the extracted solution under different analytical condition showed the possibility of existence of both repressive and promotive substances which were produced by styles before and after pollen germination and pollen tube growth began on the stigma, respectively. However, no distinct relationship between the production of those substances and the development of ovules was indicated. Therefore, it was concluded that pollen germination and pollen tube growth on the stigma were regulated by the substances produced from stigma and style themselves.