Biological Institute, College of Liberal Arts, Kagoshima University, Korimoto 1-21-30, Kagoshima 890, Japan.
Plant Physiol. 1986 Aug;81(4):980-3. doi: 10.1104/pp.81.4.980.
When etiolated radish (Raphanus sativus var. hortensis f. gigantissimus Makino) hypocotyls were subjected to a continuous unilateral illumination with white fluorescent light (0.1 watt per square meter), the growth rate at the lighted side was strongly inhibited for the first 2 hours, while that at the shaded side showed no change. After 2.5 hours growth on the lighted side recovered gradually, while that on the shaded side was slightly inhibited. The neutral growth inhibitors, cis- and trans-raphanusanins and raphanusamide, were determined in the lighted and shaded sides from 1 hour before until 2 hours after the start of unilateral illumination. In the lighted side, cis- and trans-raphanusanins increased by 0.5 hour after the start of illumination, reached 3 to 3.5-fold greater concentrations than in the shaded side after 1 hour, and then decreased gradually. Raphanusamide increased in the lighted side to a 3-fold greater concentration than that in the shaded one 2 hours after the start of the illumination. Unilateral applications of cis- and trans-raphanusanins and raphanusamide suppressed the growth of the hypocotyl on the applied side more than that on the opposite one, causing the hypocotyls to bend towards the site of application. The data suggest that phototropic curvature in radish is caused by the light-induced synthesis of growth-inhibiting cis- and trans-raphanusanins, and raphanusamide at the site of illumination.
当萝卜（Raphanus sativus var. hortensis f. gigantissimus Makino）下胚轴在持续的单侧白光照射下（每平方米 0.1 瓦特），受光侧的生长速度在前 2 小时受到强烈抑制，而遮光侧则没有变化。2.5 小时后，受光侧的生长逐渐恢复，而遮光侧的生长则略有抑制。在单侧光照开始前 1 小时到开始后 2 小时，测定了受光侧和遮光侧的中性生长抑制剂顺式和反式莱菔素以及莱菔酰胺。在受光侧，顺式和反式莱菔素在光照开始后 0.5 小时增加，1 小时后达到遮光侧的 3 至 3.5 倍，然后逐渐减少。莱菔酰胺在受光侧的浓度增加到遮光侧的 3 倍，在光照开始后 2 小时达到最大值。顺式和反式莱菔素以及莱菔酰胺的单侧应用抑制了下胚轴在应用侧的生长，比在对侧更明显，导致下胚轴向应用部位弯曲。这些数据表明，萝卜的向光性弯曲是由光照诱导的生长抑制性顺式和反式莱菔素和莱菔酰胺在光照部位的合成引起的。
