Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green
Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green
复制标题
DOI：
10.1093/pcp/pcp034
复制
发表时间：
2009-04-01
影响因子：
4.9
通讯作者：
Oguchi, Riichi
中科院分区：
文献类型：
--
作者：
Terashima, Ichiro;Fujita, Takashi;Oguchi, Riichi
文献和我们目前的研究表明，在大多数情况下，叶内光吸收曲线比光合能力曲线陡峭。因此，在强白色光下，靠近被照表面的上部叶绿体的光合作用量子产率低于下部叶绿体。因为绿色光比红光或蓝光更能穿透到叶片中，所以在强白色下，由下部叶绿体吸收的任何额外的绿色光将比额外的红光或蓝光更大程度地增加叶片光合作用。在评价附加单色光对叶片光合作用影响的基础上，提出了一种量化白色光中任意单色光效率的微分量子产额方法。将该方法应用于向日葵叶片清楚地表明，在中等至强的白色光下，绿色光比红光更有效地驱动光合作用。绿色叶应该有相当大体积的叶绿体，以容纳低效的羧化酶Rubisco，并向所有叶绿体提供适当的光。通过利用对绿色光吸收较弱的叶绿素，改变叶肉结构和调整Rubiscochlorophyll比率，叶片似乎满足两个有点矛盾的要求：增加光合有效辐射的吸收率，并在所有叶绿体中有效地驱动光合作用。我们还讨论了一些严重的问题，所造成的忽略这些叶内配置文件时，估计全叶电子传递速率和评估荧光技术的光抑制。
The literature and our present examinations indicate that the intra-leaf light absorption profile is in most cases steeper than the photosynthetic capacity profile. In strong white light, therefore, the quantum yield of photosynthesis would be lower in the upper chloroplasts, located near the illuminated surface, than that in the lower chloroplasts. Because green light can penetrate further into the leaf than red or blue light, in strong white light, any additional green light absorbed by the lower chloroplasts would increase leaf photosynthesis to a greater extent than would additional red or blue light. Based on the assessment of effects of the additional monochromatic light on leaf photosynthesis, we developed the differential quantum yield method that quantifies efficiency of any monochromatic light in white light. Application of this method to sunflower leaves clearly showed that, in moderate to strong white light, green light drove photosynthesis more effectively than red light. The green leaf should have a considerable volume of chloroplasts to accommodate the inefficient carboxylation enzyme, Rubisco, and deliver appropriate light to all the chloroplasts. By using chlorophylls that absorb green light weakly, modifying mesophyll structure and adjusting the Rubiscochlorophyll ratio, the leaf appears to satisfy two somewhat conflicting requirements: to increase the absorptance of photosynthetically active radiation, and to drive photosynthesis efficiently in all the chloroplasts. We also discuss some serious problems that are caused by neglecting these intra-leaf profiles when estimating whole leaf electron transport rates and assessing photoinhibition by fluorescence techniques.