Optical properties of rhodoxanthin accumulated in Aloe arborescens Mill. leaves under high-light stress with special reference to its photoprotective function
Optical properties of rhodoxanthin accumulated in Aloe arborescens Mill. leaves under high-light stress with special reference to its photoprotective function
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DOI：
10.1039/b417802e
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发表时间：
2005-01-01
影响因子：
3.1
通讯作者：
Pogosyan, S
中科院分区：
文献类型：
--
作者：
Merzlyak, M;Solovchenko, A;Pogosyan, S
木立芦荟中。叶子、强烈的阳光或其与干旱的结合会诱导红色酮类胡萝卜素、紫松果黄素的积累。同时，发生叶绿体向有色体的转变，伴随着类囊体膜的降解和大尺寸和数量的质体球的形成。根据胁迫条件，紫松素的积累会随着叶绿素的损失而发生，或者在叶子中色素含量相对较高的背景下发生。显微分光光度测量表明，在叶子适应强烈阳光的过程中，存在无叶绿素质体和类胡萝卜素的保留。质体光谱包含高等植物类胡萝卜素和紫松素的共同吸收带，吸收最大值分别位于光谱的蓝色（440-480 nm）和绿色范围。对全叶光学特性的研究揭示了紫松果黄素在蓝绿色范围内的宽带吸收，峰值在 540 - 550 nm 附近。在这个光谱带内，质球中发生的紫松果黄素的积累可能显着增加了受胁迫的芦荟叶片的光吸收。讨论了紫松果黄素和其他类胡萝卜素作为内部光陷阱的可能的光保护功能，类似于其他植物物种中花青素所实现的功能。
In Aloe arborescens Mill. leaves, strong sunlight or its combination with drought induces the accumulation of the red keto-carotenoid, rhodoxanthin. Simultaneously, the transformation of chloroplasts into chromoplasts accompanied by degradation of thylakoid membranes and formation of plastoglobuli, large in size and number, takes place. Depending on stress conditions the build up of rhodoxantin occurred along with the loss of chlorophyll or on the background of relatively high content of the pigment in the leaves. Microspectrophotometrical measurements showed the presence of chlorophyll-free plastids and retention of carotenoids during leaf adaptation to strong sunlight. The plastid spectra contained absorption bands of common for higher plants carotenoids together with those of rhodoxantin, with absorption maxima situated in the blue ( 440 - 480 nm) and the green ranges of the spectrum, respectively. The studies of whole-leaf optical properties revealed a broad band of rhodoxanthin absorption in the blue - green range peaking near 540 - 550 nm. Within this spectral band the accumulation of rhodoxanthin occurring, probably, in plastoglobuli considerably increased light absorption by stressed Aloe leaves. A possible photoprotective function of rhodoxanthin and other carotenoids as an internal light trap analogous to that accomplished by anthocyanins in other plant species is discussed.