PHOTOINHIBITION AND ZEAXANTHIN FORMATION IN INTACT LEAVES - A POSSIBLE ROLE OF THE XANTHOPHYLL CYCLE IN THE DISSIPATION OF EXCESS LIGHT ENERGY
PHOTOINHIBITION AND ZEAXANTHIN FORMATION IN INTACT LEAVES - A POSSIBLE ROLE OF THE XANTHOPHYLL CYCLE IN THE DISSIPATION OF EXCESS LIGHT ENERGY
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DOI：
10.1104/pp.84.2.218
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发表时间：
1987-06-01
期刊：
影响因子：
7.4
通讯作者：
CZYGAN, FC
中科院分区：
文献类型：
--
作者：
DEMMIG, B;WINTER, K;CZYGAN, FC
用脉冲调幅荧光计测量的叶绿素 a 荧光和叶子色素成分的比较研究表明，玉米黄质（一种在叶黄素循环中形成的类胡萝卜素）在保护光合作用装置免受过度光照的不利影响方面具有特殊作用。这一结论基于以下发现：（a）将香脂、常春藤和龟背竹的叶子暴露于过量的激发能量（强光、空气；弱光、2% O2、0% CO2）导致玉米黄质的大量形成和紫黄质的减少。在各种条件下，变量 Fv 或最大荧光 FM 与叶子的玉米黄质含量之间存在线性关系。 (b)当暴露于空气中的光抑制光水平时，H.helix的遮荫叶比M.deliciosa的遮荫叶具有更高的形成玉米黄质的能力，但以牺牲β-胡萝卜素为代价。荧光特性的变化表明，在 H. helix 中，对强光的主要反应是非辐射能量耗散率的增加，而在 M. deliciosa 中，对光系统 II 反应中心的光抑制损伤是主要效应。 (c) 将香脂太阳叶暴露在 2% O2 和 0% CO2 中增加的光子通量密度中，最初导致玉米黄质水平增加（与紫黄质减少相匹配），并伴随着表明非辐射能量耗散增加的荧光变化。在高于未观察到玉米黄质浓度进一步增加的光水平时，荧光特性表明存在光抑制损伤。 (d) 在室温下用调制荧光技术测定的可变荧光与最大荧光之比 FV/FM 与 O2 释放的光子产率之间获得了线性关系，类似于先前关于 77 K 叶绿素荧光特性和光合作用光子产率的发现 (O Bjorkman, B Demmig 1987 Planta 170: 489-504)。
Comparative studies of chlorophyll a fluorescence, measured with a pulse amplitude modulated fluorometer, and of the pigment composition of leaves, suggest a specific role of zeaxanthin, a carotenoid formed in the xanthophyll cycle, in protecting the photosynthetic apparatus against the adverse effects of excessive light. This conclusion is based on the following findings: (a) exposure of leaves of Populus balsamifera, Hedera helix, and Monstera deliciosa to excess excitation energy (high light, air; weak light, 2% O2, 0% CO2) led to massive formation of zeaxanthin and a decrease in violaxanthin. Over a wide range of conditions, there was a linear relationship between either variable, Fv, or maximum fluorescence, FM, and the zeaxanthin content of leaves. (b) When exposed to photoinhibitory light levels in air, shade leaves of H. helix had a higher capacity for zeaxanthin formation, at the expense of .beta.-carotene, than shade leaves of M. deliciosa. Changes in fluorescence characteristics suggested that, in H. helix, the predominant response to high light was an increase in the rate of nonradiative energy dissiation, whereas, in M. deliciosa, photoinhibitory damage to photosystem II reaction centers was the prevailing effect. (c) Exposure of a sun leaf of P. balsamifera to increasing photon flux densities in 2% O2 and 0% CO2 resulted initially in increasing levels of zeaxanthin (matched by decreases in violaxanthin) and was accompanied by fluorescence changes indicative of increased nonradiative energy dissipation. Above the light level at which no further increase in zeaxanthin concent was observed, fluorescence characteristics indicated photoinhibitory damage. (d) A linear relationship was obtained between the ratio of variable to maximum fluorescence, FV/FM, determined with the modulated fluorescence technique at room temperature, and the photon yield of O2 evolution, similar to previous findings (O Bjorkman, B Demmig 1987 Planta 170: 489-504) on chlorophyll fluorescence characteristics at 77 K and the photon yield of photosynthesis.