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首页> 外文期刊>The New Phytologist >C4 leaf curling - coupling incident light, stomatal and photosynthetic asymmetries.
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C4 leaf curling - coupling incident light, stomatal and photosynthetic asymmetries.

机译：C 4 叶片卷曲-耦合入射光，气孔和光合不对称。

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Leaf curling, most often interpreted as a response to water stress, represents a dynamic behavioural response in plants whereby the normal sunlight orientation of the 2 leaf surfaces may be reversed. The large majority of plant species (those with the C3 metabolic pathway) have leaves that are oriented approximately horizontally and have and accompanying asymmetry (dorso-ventral) in both external morphology and internal anatomy. This leaf asymmetry generates the well-known sun vs. shade leaf structure that can function to increase the overlap of absorbed sunlight and CO2 inside the leaf, and thus photosynthetic efficiency. In particular, species with C4 metabolism often have a distinct Kranze internal anatomy (chlorophyll-containing cells concentrated around vascular bundles) that is perceived as not having the structural capability to regulate the distribution of absorbed sunlight inside the leaf. CO2-concentrating mechanisms and increased phloem loading are known to contribute to high photosynthesis in C4 species, particularly in high sunlight environments. In this issue [see New Phytologist (2007) 177, 186-198], an imaginative and thorough set of experiments showing that a C4 grass species, during natural leaf curling that reversed the orientation of the upper and lower leaf surfaces, had accompanying stomatal and biochemical changes inside the leaf that enhanced its photosynthetic capability. Remarkably, stomata closed on the opposite, newly-shaded side of the leaf, while adjacent cells appeared completely inactivated photosynthetically. This dramatic asymmetry in stomatal and photosynthetic function occurred only when the lower leaf surface became illuminated via curling. The photosynthetic response to sunlight incidence on a particular leaf side was not based on leaf structural differences determined during leaf development, as commonly reported in C3 species. Instead, a more dynamic, biochemical response occurred that linked sunlight incidence to the behaviour of stomata and photosynthetic cells throughout the full thickness of the leaf. This rapid response capability during leaf curling suggests an alternative adaptive venue in C4 plants, one that is much more temporally dynamic than the developmentally determine changes in leaf structure found in C3 plants (i.e. sun/shade leaves). Photosynthetic enzymes (e.g. RUBISCO [ribulose-bisphosphate carboxylase] and phosphoenolpyruvate carboxylase) were also activated in photosynthetic cells near the sunlit surface with open stomata, where both light intensity and CO2 concentration were high.
机译：叶片卷曲最常被解释为对水分胁迫的响应，代表植物中的动态行为响应，由此可以反转两个叶片表面的正常阳光方向。绝大多数植物物种（具有C 3 代谢途径的植物）的叶子都大约水平定向，并且在外部形态和内部解剖结构上均具有不对称性（背腹）。这种叶片的不对称性产生了众所周知的日照与阴凉的叶片结构，可以增加吸收的阳光和叶片内部CO 2 的重叠，从而提高光合效率。特别是，具有C 4 代谢的物种通常具有独特的Kranze内部解剖结构（包含维管束周围的含叶绿素细胞），其结构能力无法调节被吸收的阳光在植物体内的分布。叶。已知CO 2 富集机制和韧皮部负载的增加有助于C 4 物种的高光合作用，特别是在高日照环境中。在本期杂志中[请参阅新植物学家（2007） 177 ，186-198]，一组富有想象力和全面的实验表明C 4 草种在自然的叶子卷曲过程中颠倒了上下叶子表面的方向，在叶子内部伴随着气孔和生化变化，从而增强了其光合能力。值得注意的是，气孔在叶片的另一侧新阴影的一侧闭合，而相邻的细胞似乎完全被光合灭活。这种气孔和光合功能的显着不对称性仅在下部叶片表面通过卷曲而被照亮时发生。正如在C 3 物种中普遍报道的那样，对特定叶片侧的阳光入射的光合作用响应并非基于叶片发育过程中确定的叶片结构差异。取而代之的是，发生了更加动态的生化反应，将阳光的入射与整个叶片整个厚度上的气孔和光合细胞的行为联系在一起。叶片卷曲过程中的这种快速响应能力表明了C 4 植物中的另一种适应性场所，该场所在时间上比在C 3 中发现的叶片结构变化具有动态决定性。植物（即遮阳/遮荫的叶子）。光合酶（如RUBISCO [核糖二磷酸羧化酶]和磷酸烯醇丙酮酸羧化酶）也被活化的光合细胞在靠近气孔的阳光表面附近激活，其中光强度和CO 2 浓度都很高。

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