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首页> 外文期刊>Annals of Botany >Causes of decreased photosynthetic rate and metabolic capacity in water-deficient leaf cells: a critical evaluation of mechanisms and integration of processes
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Causes of decreased photosynthetic rate and metabolic capacity in water-deficient leaf cells: a critical evaluation of mechanisms and integration of processes

机译：缺水叶细胞光合速率和代谢能力下降的原因：对机制和过程整合的严格评估

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BACKGROUND: Water deficit (WD) decreases photosynthetic rate (A) via decreased stomatal conductance to CO(2) (g(s)) and photosynthetic metabolic potential (A(pot)). The relative importance of g(s) and A(pot), and how they are affected by WD, are reviewed with respect to light intensity and to experimental approaches. SCOPE AND CONCLUSIONS: With progressive WD, A decreases as g(s) falls. Under low light during growth and WD, A is stimulated by elevated CO(2), showing that metabolism (A(pot)) is not impaired, but at high light A is not stimulated, showing inhibition. At a given intercellular CO(2) concentration (C(i)) A decreases, showing impaired metabolism (A(pot)). The C(i) and probably chloroplast CO(2) concentration (C(c)), decreases and then increases, together with the equilibrium CO(2) concentration, with greater WD. Estimation of C(c) and internal (mesophyll) conductance (g(i)) is considered uncertain. Photosystem activity is unaffected until very severe WD, maintaining electron (e(-)) transport (ET) and reductant content. Low A, together with photorespiration (PR), which is maintained or decreased, provides a smaller sink for e(-)(,) causing over-energization of energy transduction. Despite increased non-photochemical quenching (NPQ), excess energy and e(-) result in generation of reactive oxygen species (ROS). Evidence is considered that ROS damages ATP synthase so that ATP content decreases progressively with WD. Decreased ATP limits RuBP production by the Calvin cycle and thus A(pot). Rubisco activity is unlikely to determine A(pot). Sucrose synthesis is limited by lack of substrate and impaired enzyme regulation. With WD, PR decreases relative to light respiration (R(L)), and mitochondria consume reductant and synthesise ATP. With progressing WD at low A, R(L) increases C(i) and C(c). This review emphasises the effects of light intensity, considers techniques, and develops a qualitative model of photosynthetic metabolism under WD that explains many observations: testable hypotheses are suggested.
机译：背景：缺水（WD）通过降低气孔对CO（2）（g（s））的气孔导度和光合代谢潜能（A（pot））降低光合速率（A）。关于光强度和实验方法，对g（s）和A（pot）的相对重要性以及它们如何受WD影响进行了综述。范围和结论：进行性WD时，A随着g（s）的下降而降低。在生长和WD的弱光下，CO被升高的CO（2）刺激，这表明新陈代谢（A（pot））不会受到损害，但是在强光下，A不会受到刺激，显示出抑制作用。在给定的细胞间CO（2）浓度（C（i））下，A降低，表明代谢受损（A（pot））。 C（i）和可能的叶绿体CO（2）浓度（C（c））先降低后升高，再加上平衡WD（2）的平衡CO（2）浓度。 C（c）和内部（间位）电导（g（i））的估计被认为是不确定的。在非常严重的WD之前，光系统的活动不会受到影响，保持电子（e（-））传输（ET）和还原剂含量。低A与维持或减少的光呼吸（PR）一起，为e（-）（，）提供了一个较小的吸收区，从而导致能量转换过度激发。尽管增加了非光化学猝灭（NPQ），但是过剩的能量和e（-）会导致产生活性氧（ROS）。有证据表明，ROS会破坏ATP合酶，因此WD会使ATP含量逐渐降低。 ATP的降低会限制卡尔文循环的RuBP生成，从而限制A（pot）。 Rubisco活性不太可能确定A（pot）。缺乏底物和酶调节受损，限制了蔗糖的合成。对于WD，PR相对于光呼吸（R（L））降低，线粒体消耗还原剂并合成ATP。随着WD在低A处进行，R（L）增加C（i）和C（c）。这篇评论强调光强度的影响，考虑技术，并开发了WD下光合作用代谢的定性模型，该模型解释了许多观察结果：提出了可检验的假设。

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