School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Plant Physiol. 1991 Jul;96(3):761-7. doi: 10.1104/pp.96.3.761.
Cucumber (Cucumis sativus L. cv Poinsette) plants were sprayed with 20 millimolar 5-aminolevulinic acid (ALA) and then incubated in dark for 14 hours. Upon transfer to sunlight ( approximately 800 watts per square meter) the plants died after 5 hours of exposure due to photosensitization reaction of metalloporphyrins. Due to the photodynamic damage, photosystem II (PSII), photosystem I (PSI), and whole chain reactions were impaired. PSII activity was more susceptible to photodynamic damage than PSI. The variable fluorescence was significantly reduced in ALA-treated plants within 1 hour of exposure to sunlight. At low temperature (77 degrees K), the PSI fluorescence peak height (F(734)) was drastically reduced and blue shifted by 6 nanometers. The photodynamic damage was irreversible; rather, it continued upon dark incubation of ALA-treated cucumber plants exposed to sunlight for 15 minutes. In the latter experiment, continued production of malondialdehyde during dark treatment suggests the degradation of unsaturated membrane lipids.
黄瓜（Cucumis sativus L. cv Poinsette）植株经 20 毫摩尔 5-氨基乙酰丙酸（ALA）喷雾处理后，在黑暗中孵育 14 小时。当转移到阳光（约每平方米 800 瓦）下时，由于金属卟啉的光致敏反应，植物在暴露 5 小时后死亡。由于光动力损伤，光系统 II（PSII）、光系统 I（PSI）和整个链式反应受到损害。PSII 活性比 PSI 更容易受到光动力损伤的影响。ALA 处理的植物在暴露于阳光 1 小时内，可变荧光显著降低。在低温（77 开尔文）下，PSI 荧光峰高度（F（734））明显降低，并蓝移 6 纳米。光动力损伤是不可逆的；相反，在黑暗中孵育暴露于阳光 15 分钟的 ALA 处理的黄瓜植物时，它会继续进行。在后一个实验中，在黑暗处理期间持续产生丙二醛表明不饱和膜脂质的降解。
