Mechanisms underlying interspecific variation in photosynthetic capacity across wild plant species
Mechanisms underlying interspecific variation in photosynthetic capacity across wild plant species
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DOI：
10.5511/plantbiotechnology.27.223
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发表时间：
2010-01-01
影响因子：
1.6
通讯作者：
Hikosaka, Kouki
中科院分区：
文献类型：
--
作者：
Hikosaka, Kouki
尽管C（3）物种具有相同的光合代谢，但它们的叶片光合能力差异很大。在这里，我们讨论光合能力种间变异的机制。种内光合能力的变化一般是由氮浓度解释，因为光合氮利用效率（PNUE，每单位叶氮的光合能力）往往是恒定的，在每个物种。另一方面，种间变异涉及氮浓度和PNUE的变化。具有较高光合能力的植物单位质量氮浓度和PNUE较高。PNUE的种间差异与CO（2）在叶片中的扩散、氮素在光合机构中的分配和/或光合酶的比活性有关。以往的研究表明，叶肉导度和氮素分配的变化可以解释PNUE的变化。由于新叶是由同化的氮和碳构成的，增加的碳同化率预计会稀释叶片中的氮。然而，这一预期与光合能力和氮浓度在物种间呈正相关的事实相矛盾。这种矛盾的稀释效应可以通过根系活性来补偿，即具有较高光合能力的物种具有较高的根系活性以维持较高的叶片氮浓度。
Photosynthetic capacity of leaves varies greatly among C(3) species although they have the same photosynthetic metabolisms. Here we discuss mechanisms underlying interspecific variation in photosynthetic capacity. Within-species variation in photosynthetic capacity is generally explained by nitrogen concentration because photosynthetic nitrogen-use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) tends to be constant in each species. Among-species variation, on the other hand, involves both variations in nitrogen concentration and PNUE. Species with higher photosynthetic capacity have higher nitrogen concentration per mass and PNUE. Interspecific variation in PNUE is attributable to CO(2) diffusion in the leaves, nitrogen allocation to the photosynthetic apparatus and/or specific activity of photosynthetic enzymes. Previous studies have shown that variations in mesophyll conductance and nitrogen allocation explain the variation in PNUE. As new leaves are constructed by assimilated nitrogen and carbon, increased carbon assimilation rates are expected to dilute nitrogen in the leaves. However, this expectation contradicts the fact that photosynthetic capacity and nitrogen concentration is positively related with each other across species. This paradoxical dilution effect may be compensated by root activity, i.e. species with higher photosynthetic capacity have higher root activity to maintain higher leaf nitrogen concentrations.