植物生理学论文--低温对植物光合作用的影响

1.2. Photoprotection and downregulation (dynamic photoinhibition) The rapidly reversible downregulation of PSII quantum efficiency plays an indispensable photoprotective role in leaves. This process involves the interconversion of xanthophyll pigments and the development of a transthylakoid proton electrochemical potential difference, and is clearly a crucial protective measure against the more pernicious impact of photodamage . Changes in the quenching of excitation energy in the antennae of PSII can easily be estimated using modulated chlorophyll fluorescence. Both Fv′/Fm′ (the efficiency of excitation energy transfer to open PSII reaction centers) and nonphotochemical quenching are parameters widely used to quantify this downregulation of PSII electron transport. 1.2 光保护和下调（动态光抑制） 在叶片中，PSII量子效率的快速可逆的下调起到不可或缺的光保护 作用。这个过程涉及叶黄素的互变和质子跨膜电化学电势差的发展， 并显然是针对光损伤至关重要的保护措施。可以很容易地使用调制 叶绿素荧光估计在PSII的天线色素激发能量的改变。Fv ' / FM '和非 光化学淬灭是广泛用于量化该PSII的电子传输的参数。
1. Thylakoid electron transport 1.1. Photodamage (chronic photoinhibition) and repair Its ease of measurement means that the ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) in dark-adapted leaves is often used to identify photosystem II (PSII) photodamage, an inhibition of PSII photochemistry that is not rapidly reversible. The amount of that can bind to the plastoquinone-reductase site of PSII in isolated thylakoids, produces a more direct and quantitative assessment . 1，类囊体膜上的电子传递 1.1光损伤（慢性光抑制）和修复 在暗适应的条件下，叶绿素荧光（FV/ FM）的比值经常被 用于识别光系统II（PSII）的光损伤，PSII光化学抑制是不能快 速逆转的。在孤立的类囊体上，C-阿特拉津（C-atrazine）可 以绑定到PSII的质体醌还原酶上，并计算其数量，产生更直接 定量的对光损伤评估。
这已经被归因于改变psbA基因（质体基因）的表达，其编码D1蛋白和膜 上直接温度效应的表达。低温降低了膜的流动性，因此被认为光损伤是通过 降低D1的扩散速率，以减少D1的周转率。通过遗传操作类囊体的膜脂，以 减少脂肪酸的饱和度可以部分减轻高光低温条件下的光抑制，大概是通过增 强扩散，从而促进修复。然而，PSII的光损伤往往不是抑制光合作用主要原 因。
167940010 张东芳
Abstract
• Photosynthesis in warm-climate plants is substantially reduced after chilling. Tropical and subtropical species offer the opportunity to study the effects of low temperature on photosynthetic processes undisguised by the myriad of protective responses observed in temperate species. In this article, we highlight the primary components of photosynthesis that are affected by a short chill, in both the dark and the light, and discuss what is known of the mechanisms involved. Recent work implicates impaired redox and circadian regulation among other processes. • 在低温处理的情况下，热带植物的光合作用效率大幅降低。 热带和亚热带的物种为我们研究低温对各物种光合作用过 程的影响提供一个机会。在这篇文章中，我们强调由一个 短暂的低温处理和黑暗或光照的组合影响的光合作用，并 讨论什么是已知参与的机制。最近的研究发现其中包括氧 化还原受损和昼夜调控。
Impacts of chilling temperatures on photosynthesis in warm-climate plants 低温对热带植物光合作用的影响
Trends in Plant Science, Volume 6, Issue 1, 1 January 2001, Pages 36-42
缩写： ATPsynthase， 叶绿体ATP合酶 B6F，细胞色素 b6f复合体 RuBP，核酮糖 1,5 - 二磷酸 FBP酶，叶绿 体果糖-1,6 - 二 磷酸酶 SBPase，景天 庚酮糖1,7 - 二 磷酸酶 淡蓝色的剪刀 代表了光照与 低温组合的影 响 深蓝色的剪刀 代表一个黑暗 与低温组合的 主要影响
This has been attributed to changes in the expression of psbA, the plastid gene that encodes D1, and direct temperature effects on membranes . Low temperature reduces membrane fluidity and thus is believed to reduce the rate of D1 turnover by slowing the diffusion of photodamaged D1 proteins marked for degradation to non-appressed regions of the thylakoid. Genetic manipulation of thylakoid lipids to decrease the saturation of fatty acids can partially mitigate high-light–low-temperature photoinhibition , presumably by enhancing diffusion and thereby facilitating repair. Nevertheless, photodamage of PSII is frequently not primarily responsible for light-chill-induced inhibition of photosynthesis in thermophilic plants.
Keywords/关键字
• Low temperature; Photoinhibition; Oxidative stress; Carbon reduction cycle; Circadian rhythm • 低温;光抑制;氧化应激;减碳循环;昼夜节律
ຫໍສະໝຸດ Baidu
Low temperature is a major factor limiting the productivity and geographical distribution of many species, including important agricultural crops. The formation of ice inside plant cells is devastating. Freeze-tolerant plants have several strategies to reduce the probability of this occurring, even when air temperature drops below zero, including maintaining high intracellular solute concentrations and encouraging ice nucleation outside the cells. These plants also commonly exhibit xerophytic adaptations to survive the reduced water availability within the plant and the soil. Temperatures of −5°C can kill an unhardened winter wheat plant even though it has the genetic capacity to acclimatize, harden and acquire tolerance of freezing down to −20°C. The cold-hardening mechanisms conferring freeze tolerance have been described elsewhere. and include changes in lipid composition, increases in activeoxygen-scavenging enzymes, anthocyanin accumulation and altered growth morphology. 低温是限制了许多物种的产量和地理分布的一个主要因素，其中包括重要 的农业作物。在植物细胞内冰的形成是毁灭性的。植物对冷冻有多种策略， 以减少这种情况发生的概率，即使在气温降到零度以下，策略包括维持细 胞内高浓度的溶质。这些植物通常也表现出适应旱生。 -5 °C的温度可以杀 死一个未硬化的冬季小麦植株即使它有适应环境，硬化，并获得冷冻低至20 °C 的耐受性遗传能力。赋予冷冻硬化的机制已在别处描述。
Photodamage is rarely observed immediately after chilling of even the most extreme thermophilic species if low temperatures are experienced in the dark .By contrast, the combination of low temperature with high light has the potential to induce chronic photoinhibition of PSII (Fig. 1). This is partly because lowering the temperature generally reduces reaction rates and can therefore limit the sinks for the absorbed excitation energy (light), particularly CO2 fixation and photorespiration. Smaller sinks for absorbed excitation energy increases the potential for oxidative damage to PSII, notably the D1 component of the D1–D2 heterodimer at the core of the PSII functional center. In addition, photodamage becomes apparent as low temperatures interfere with the normal replacement rate of D1 in the turnover–repair cycle. 在黑暗中经历低温后，即使是最喜光的物种遭遇冷害，光损伤是很少 被看到。相比之下，低温与强光的组合具有诱导光系统II的光抑制（光 损伤）的潜力。（图1）这部分是由于降低温度通常会降低反应速率， 因此可以限制接收器吸收激发能量（光），特别是CO 2固定和光呼吸。 因为接收器吸收的激发能量较小，因此增加了对PSII的氧化损伤的潜力， 特别是在PSII官能中心的D1-D2二聚体​芯部的D1组件。此外，光损伤变 得明显，因为低温会干扰D1的正常反应速率。