TEMPERATURE-SENSITIVE COUPLING AND UNCOUPLING OF ATPASE-MEDIATED, NONRADIATIVE ENERGY-DISSIPATION - SIMILARITIES BETWEEN CHLOROPLASTS AND LEAVES
TEMPERATURE-SENSITIVE COUPLING AND UNCOUPLING OF ATPASE-MEDIATED, NONRADIATIVE ENERGY-DISSIPATION - SIMILARITIES BETWEEN CHLOROPLASTS AND LEAVES
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DOI：
10.1007/bf00191573
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发表时间：
1995-11-01
期刊：
影响因子：
4.3
通讯作者：
BJORKMAN, O
中科院分区：
文献类型：
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作者：
GILMORE, AM;BJORKMAN, O
比较了温度对生菜（Lactuca sativa L.）叶绿体和环叶青（Aegialitis annulata R. Br）叶片光系统II非辐射能量耗散暗松弛动力学的影响。在光照条件下，高水平的紫黄素去环氧化处理后，叶黄炎叶片的非辐射耗散暗松弛明显延迟，这是通过光系统II叶绿素a荧光的非光化学猝灭（NPQ）来测量的。在强光照射期间和之后的低温条件下，剑齿苋叶片也保持了较高的腺苷酸能量电荷，这可能是由于其有限的固碳能力。同样，生菜叶绿体在去环氧紫黄质和光激活ATP合成酶后，也能诱导持续黑暗的NPQ。低温对叶片和叶绿体的暗持续NPQ的持续时间和程度均有显著影响。此外，在低温下维持的NPQ在变暖后迅速逆转。在生菜叶绿体中，低温急剧降低了atp水解速率，同时增加了引发NPQ的反式类囊体质子梯度的持续时间和程度。这与较高程度的能量耦合是一致的，可能是由于在较低温度下质子通过类囊体膜的扩散减少了。叶绿体腺苷酸池与腺苷酸激酶处于平衡状态，因此ATP和ADP都参与了反向偶联，低温增强的NPQ在叶绿体和叶片中按比例猝灭了暗水平（F-o）和最大荧光（F-m）的产量。在黑暗中NPQ的程度与光系统II的效率呈负相关，并且在很宽的温度范围内叶绿体和叶片中都获得了非常相似的线性关系。同样，紫黄质去环氧化（A(508 nm)）和能量依赖光散射（A(536) nm）引起的黑暗持续吸光度变化在叶绿体和叶片中惊人地相似。因此，我们得出结论，叶绿体和叶片中持续黑暗、低温刺激的NPQ显然直接依赖于管腔酸化和叶绿体ATP水解。在叶片中，维持NPQ所需的ATP显然是由线粒体的氧化磷酸化提供的。讨论了这种猝灭过程的功能意义及其对叶片光保护和光损伤测量的意义。
The effects of temperature on the dark relaxation kinetics of nonradiative energy dissipation in photosystem II were compared in lettuce (Lactuca sativa L.) chloroplasts and leaves of Aegialitis annulata R. Br. After high levels of violaxanthin de-epoxidation in the light, Aegialitis leaves showed a marked delay in the dark relaxation of nonradiative dissipation, measured as nonphotochemical quenching (NPQ) of photosystem II chlorophyll a fluorescence. Aegialitis leaves also maintained a moderately high adenylate energy charge at low temperatures during and after high-light exposure, presumably because of their limited carbon-fixation capacity. Similarly, dark-sustained NPQ could be induced in lettuce chloroplasts after de-epoxidizing violaxanthin and light-activating the ATP synthase. The duration and extent of dark-sustained NPQ were strongly enhanced by low temperatures in both chloroplasts and leaves. Further, the NPQ sustained at low temperatures was rapidly reversed upon warming. In lettuce chloroplasts, low temperatures sharply decreased the ATP-hydrolysis rate while increasing the duration and extent of the resultant trans-thylakoid proton gradient that elicits the NPQ. This was consistent with a higher degree of energy-coupling, presumably due to reduced proton diffusion through the thylakoid membrane at the lower temperatures. The chloroplast adenylate pool was in equilibrium with the adenylate kinase and therefore both ATP and ADP contributed to reverse coupling, The low-temperature-enhanced NPQ quenched the yields of the dark level (F-o) and the maximal (F-m) fluorescence proportionally in both chloroplasts and leaves. The extent of NPQ in the dark was inversely related to the efficiency of photosystem II, and very similar linear relationships were obtained over a wide temperature range in both chloroplasts and leaves. Likewise, the dark-sustained absorbance changes, caused by violaxanthin de-epoxidation (A(508 nm)) and energy-dependent light scattering (A(536) nm) were strikingly similar in chloroplasts and leaves. Therefore, we conclude that the dark-sustained, low-temperature-stimulated NPQ in chloroplasts and leaves is apparently directly dependent on lumen acidification and chloroplastic ATP hydrolysis. In leaves, the ATP required for sustained NPQ is evidently provided by oxidative phosphorylation in the mitochondria. The functional significance of this quenching process and implications for measurements of photoprotection versus photodamage in leaves are discussed.