Department of Earth and Environmental Sciences, Columbia University, NY 10964, USA.
Plant Biol (Stuttg). 2013 Jul;15(4):769-75. doi: 10.1111/j.1438-8677.2012.00703.x. Epub 2013 Mar 1.
Plant respiratory metabolism is complicated by the fact that the rate of non-photorespiratory mitochondrial CO2 release in the light (R light) may be lower than the rate of leaf respiration in the dark (R dark). A body of work on this topic implies a linkage between light inhibition of respiration and photorespiration, although the direction of effect and underlying mechanisms remain uncertain. In this study we used a variety of short- and long-term environmental manipulations to explicitly manipulate the rate of photorespiration (νo) and quantify the effect on the inhibition of mitochondrial respiration in the light (R light:R dark). We address the following three questions: (i) will the R light:R dark ratio increase or decrease with high CO2 or low O2 and at low temperatures; (ii) does νo correlate with R light:R dark, and if so, in what way; (iii) will suppression of respiration by light (the 'Kok effect') be seen to the same extent in Zea mays, a C4 plant, and in Triticum aestivum, a C3 plant? We found that Rlight :Rdark decreased under conditions that suppressed νo in wheat, and this resulted in a positive relationship between R light:R dark and νo. Inhibition of respiration by light in C4 maize did not respond to environmental treatment, and the fixed R light:R dark (0.46-0.72) was consistent with the wheat response, assuming a νo approaching zero. The most likely mechanism to explain this finding is that R light increases (or the inhibition of respiration by light decreases) when there is an increase in photorespiration and thus an increase in the demand for TCA cycle substrates associated with the recovery of photorespiratory cycle intermediates in the peroxisome. This work is significant because it combines a comparison of C3 and C4 metabolism with a range of environmental treatments to independently suppress νo.
植物呼吸代谢很复杂，因为在光下非光呼吸线粒体 CO2 释放率（R light）可能低于黑暗中叶片呼吸率（R dark）。大量关于这个主题的研究表明，呼吸抑制与光呼吸之间存在联系，尽管效应的方向和潜在机制仍不确定。在这项研究中，我们使用了各种短期和长期的环境处理方法来明确操纵光呼吸速率（νo），并量化其对光下线粒体呼吸抑制的影响（R light：R dark）。我们提出了以下三个问题：（i）在高 CO2 或低 O2 和低温下，R light：R dark 比值会增加还是减少；（ii）νo 是否与 R light：R dark 相关，如果相关，以何种方式相关；（iii）在 C4 玉米 Zea mays 和 C3 小麦 Triticum aestivum 中，光对呼吸的抑制（“Kok 效应”）是否会以相同程度表现出来？我们发现，在抑制小麦 νo 的条件下，Rlight：Rdark 降低，这导致 R light：R dark 与 νo 之间呈正相关。C4 玉米呼吸的光抑制对环境处理没有响应，并且固定的 R light：R dark（0.46-0.72）与小麦的响应一致，假设 νo 接近零。最有可能的解释机制是，当光呼吸增加时，R light 增加（或光对呼吸的抑制减少），因此与过氧化物酶体中光呼吸循环中间体恢复相关的 TCA 循环底物的需求增加。这项工作很重要，因为它将 C3 和 C4 代谢的比较与一系列环境处理相结合，以独立抑制 νo。
