Regulation mechanism by blue light of photomorophogenesis and brassinosteroid activity

本文研究了蓝光对黄化水稻幼苗叶片倾斜及粘杆菌子实体形成的光调节机制。6种植物激素中的油菜素内酯（BS）在极低浓度和蓝光照射下对黄化水稻幼苗的叶片倾斜有显著促进作用。在蓝光照射下生长的幼苗的叶片倾斜活性比在黑暗下生长的幼苗提高了约30倍。在照射3小时内观察到蓝光效应，照射48小时后仍保持相同的效果。然而，内源性BSs的水平被确定为睾酮，斑霉甾醇，卡斯特酮和油菜素内酯。倾斜活性的增强是由BS增效剂的存在引起的。通过HPLC纯化，恢复了暗生幼苗的倾斜活性，发现暗生幼苗中存在一定的抑制因子，更能抑制BS增效剂的作用。事实表明，蓝光效应是起到分解或去除BS增效剂抑制因子的作用。BS增效剂和抑制剂均因用量少且不稳定而未能鉴定。但是我们在筛选合成化合物的过程中发现了一种BS增效剂。它可能会为鉴别天然化合物提供一些化学信息。另一方面，在革兰氏阴性菌的生命周期中，蓝光对子实体的形成是必不可少的。一种类胡萝卜素生物合成抑制剂抑制蓝光照射下子实体的形成。蓝光对果实形成初期类胡萝卜素积累的影响发生了质的变化。普遍分布于植物组织中的类胡萝卜素被认为是蓝光的可能受体之一。确定一个诱导粘球菌子实体形成的因子将为植物的光形态发生提供非常有用的信息。少

This is study on photoregulation mechanism by blue light of lamina inclination of etiolated rice seedlings and formation of fruiting body of Myxobacteria. Lamina inclination of etiolated rice seedlings was remarkably promoted by treatment with brassinosteroid (BS), the six-type of phytohormone, at a extremely low concentration and by irradiation with blue light. A lamina inclination activity in the seedlings grown under blue light irradiation was enhanced about 30 times higher than that grown under the darkness. The blue light effect was observed within 3 hr of irradiation and the same effect was maintained after 48 hr irradiation. However, the endogenous levels of BSs which were identified to be teasterone, typhasterol, castasterone and brassinolide. Enhancement of the inclination activity was caused by presence of a BS synergist. The inclination activity of seedlings grown under the darkness was recovered by means of HPLC purification, resulting presence of a certain suppressor that … More inhibits the function of BS synergist in the dark-grown seedlings. From the facts it was shown that the blue light effect is to play a role of decomposing or removing the suppressor of the BS synergist. Both of the BS synergist and its suppressor failed to identify because of a quite small amounts and unstable compound. But we found a BS synergist during screening some synthetic compounds. Probably it will offer any chemical informations for identification of the natural compound.On the other hand, blue light is essential for formation of fruiting body in a life cycle of Myxobacteria which is most evolutionary in gram negative bacteria. An inhibitor of carotenoid biosynthesis inhibited forming the fruiting body under blue light irradiation. Effect of blue light was to changing qualitatively in carotenoid accumulation at the beginning of the fruiting formation. Carotenoid commonly distributed in plant tissues has been counted to be one of a possible receptor of blue light. Assignment of a factor inducing the fruiting body formation of Myxococcus will offer very useful information as to photomorphogenesis of plants. Less