Yahubyan G, Minkov I, Sundqvist C
Department of Plant Physiology and Molecular Biology, University of Plovdiv, Tsar Assen 24 St., 4000 Plovdiv, Bulgaria.
J Photochem Photobiol B. 2001 Dec 31;65(2-3):171-6. doi: 10.1016/s1011-1344(01)00266-4.
The influence of carotenoids on partial protochlorophyllide (Pchlide) photoreduction and the successive formation of long-wavelength chlorophyllide (Chlide) forms was studied by low-temperature fluorescence spectroscopy (77 K). Wheat leaves with a decreased content of carotenoids obtained from norflurazon-treated seedlings (10 and 100 micromol l(-1)) were compared with leaves containing normal amounts of these pigments. Partial photoreduction of Pchlide was achieved by irradiation of the leaves with one light flash in combination with a number of neutral gray and/or red Perspex filters. There were significant differences between the fluorescence emission spectra (the position and height of the peaks) of dark-grown normal and carotenoid-deficient leaves irradiated with non-saturating white light of increasing intensity. The long-wavelength Chlide forms appeared first in the leaves nearly devoid of carotenoids (treated with 100 micromol l(-1) norflurazon), then in the leaves with carotenoid deficiency (treated with 10 micromol l(-1) norflurazon), and finally in normal leaves. After irradiation with non-saturating light of the same intensity, the ratio Chlide/Pchlide(657) was always the highest in the leaves nearly deficient of carotenoids, medium in the leaves with carotenoid deficiency and lowest in the normal leaves. Similarly to white light, red light of low intensity induced faster formation of long-wavelength Chlide species in the leaves with carotenoid deficiency in comparison to the normal leaves. We propose that, in leaves with reduced carotenoid content, a greater number of Pchlide molecules transform to Chlide per light flash than in normal leaves. The results are discussed in relation to the involvement of carotenoids in competitive absorption and light screening, as well as to their influence on Pchlide-Chlide interactions.
通过低温荧光光谱法（77K）研究了类胡萝卜素对部分原叶绿素酸酯（Pchlide）光还原以及长波长叶绿素酸酯（Chlide）形式的连续形成的影响。将用去草净处理的幼苗（10和100微摩尔/升）获得的类胡萝卜素含量降低的小麦叶片与含有正常量这些色素的叶片进行比较。通过用一次闪光结合多个中性灰色和/或红色有机玻璃滤光片照射叶片来实现Pchlide的部分光还原。用强度逐渐增加的非饱和白光照射的黑暗生长的正常叶片和类胡萝卜素缺乏叶片的荧光发射光谱（峰的位置和高度）之间存在显著差异。长波长Chlide形式首先出现在几乎不含类胡萝卜素的叶片中（用100微摩尔/升去草净处理），然后出现在类胡萝卜素缺乏的叶片中（用10微摩尔/升去草净处理），最后出现在正常叶片中。用相同强度的非饱和光照射后，Chlide/Pchlide(657)的比值在几乎缺乏类胡萝卜素的叶片中总是最高，在类胡萝卜素缺乏的叶片中居中，在正常叶片中最低。与白光类似，与正常叶片相比，低强度红光在类胡萝卜素缺乏的叶片中诱导长波长Chlide物种的形成更快。我们提出，在类胡萝卜素含量降低的叶片中，每次闪光转化为Chlide的Pchlide分子数量比正常叶片中更多。结合类胡萝卜素在竞争性吸收和光屏蔽中的作用以及它们对Pchlide-Chlide相互作用的影响对结果进行了讨论。
