Effects of internal conductance on the temperature dependence of the photosynthetic rate in spinach leaves from contrasting growth temperatures.
Effects of internal conductance on the temperature dependence of the photosynthetic rate in spinach leaves from contrasting growth temperatures.
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DOI：
10.1093/pcp/pcj077
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发表时间：
2006-08
影响因子：
4.9
通讯作者：
W. Yamori;K. Noguchi;Y. Hanba;I. Terashima
中科院分区：
文献类型：
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作者：
W. Yamori;K. Noguchi;Y. Hanba;I. Terashima
光合速率可能受到从细胞间隙到叶绿体基质的内部传导（g（i））的强烈限制。然而，生长和叶温对g（i）的影响仍不清楚。在这项工作中，我们确定了在30/25摄氏度（高温; HT）和15/10摄氏度（低温; LT）下生长的菠菜叶中g（i）的温度依赖性，使用气体交换速率和稳定碳同位素比的同时测量。此外，我们量化了g（i）对光合速率的温度依赖性的影响。在饱和光（A（360））下，测定了不同叶温下CO（2）浓度为360 μ l（-1）时的g（i）和光合速率。A（360）的最适温度在高温叶片中为28.5 ℃，在低温叶片中为22.9 ℃。在高温和低温下，g（i）的最适温度与A（360）相近。A（360）与g（i）之间有较强的线性关系。C（3）光合作用模型在考虑g（i）的情况下，对高温和低温叶片的光合速率的预测结果与A（360）模型吻合较好。在10 - 20 ℃之间，高温和低温叶片的g（i）的温度系数Q（10）分别为2.0和1.8。这表明g（i）不仅由物理扩散决定，而且由蛋白质促进的过程决定。在高温和低温下，g（i）对光合速率的限制随叶温的升高而增大，且在任何温度下都大于气孔导度的限制。这项研究表明，g（i）基本上限制了光合速率，特别是在较高的温度下。
The photosynthetic rate may be strongly limited by internal conductance from the intercellular airspace to the chloroplast stroma (g(i)). However, the effects of growth and leaf temperature on g(i) are still unclarified. In this work, we determined the temperature dependence of g(i) in spinach leaves grown at 30/25 degrees C (high temperature; HT) and 15/10 degrees C (low temperature; LT), using the concurrent measurements of the gas exchange rate and stable carbon isotope ratio. Moreover, we quantified the effects of g(i) on the temperature dependence of the photosynthetic rate. We measured g(i) and the photosynthetic rate at a CO(2) concentration of 360 microl l(-1) under saturating light (A(360)) at different leaf temperatures. The optimum temperature for A(360) was 28.5 degrees C in HT leaves and 22.9 degrees C in LT leaves. The optimum temperatures for g(i) were almost similar to those of A(360) in both HT and LT leaves. There was a strong linear relationship between A(360) and g(i). The photosynthetic rates predicted from the C(3) photosynthesis model taking account of g(i) agreed well with A(360) in both HT and LT leaves. The temperature coefficients (Q(10)) of g(i) between 10 and 20 degrees C were 2.0 and 1.8 in HT and LT leaves, respectively. This suggests that g(i) was determined not only by physical diffusion but by processes facilitated by protein(s). The limitation of the photosynthetic rate imposed by g(i) increased with leaf temperature and was greater than the limitation of the stomatal conductance at any temperature, in both HT and LT leaves. This study suggests that g(i) substantially limits the photosynthetic rate, especially at higher temperatures.