Leaf Structural Properties that Influence Photosynthesis: Interactions Between Gradients of Light and Photosynthetic Capacity

9409139 Vogelmann许多叶片结构特征（如栅栏和海绵状叶肉）的功能意义尚未被归因于。这些组织可能通过最大化内部光和二氧化碳浓度的重叠来优化光合作用。拟议的研究将检查叶片解剖、内部光梯度、二氧化碳和叶片内光合活性分布之间的关系。在大多数叶片中，光从顶部进入，而二氧化碳主要从底部进入，那里有大多数气孔。这可能会产生两个相反的内部梯度，其中任何一个都可能限制单个细胞层的光合作用。反过来，这种内部限制可能会影响整个叶片水平的光合作用表现。叶片解剖结构（遮阳叶片与遮阴叶片）和叶片上下表面气孔数量的变化（浅气孔与amphistomy）可能影响对光和二氧化碳的内部限制，并影响整个叶片的光合作用性能。通过使用放射性标记和显微放射自显影技术，可以更直接地研究光与叶片光合性能梯度之间的相互作用。这些实验将是了解叶片结构对农业和本地物种光合性能重要性的第一步。* * *

9409139 Vogelmann Functional significance has not been ascribed to many leaf structural features such as palisade and spongy mesophyll. These tissues presumably optimize photosynthesis, possibly by maximizing overlap between internal concentrations of light and carbon dioxide. The proposed research will examine the relationship between leaf anatomy, internal gradients of light, carbon dioxide and the distribution of photosynthetic activity within the leaf. In most leaves, light enters from the top whereas carbon dioxide enters primarily from the bottom where the majority of the stomata occur. This may create two opposing internal gradients, either one of which may limit photosynthesis of the individual cell layers. In turn, such internal limitations could influence photosynthetic performance at the level of the whole-leaf. Leaf anatomy (sun vs. shade leaves) and the placement of variable numbers of stomates on the lower and upper leaf surfaces (hypo- vs. amphistomy) could influence internal limitations to light and carbon dioxide, and affect whole-leaf photosynthetic performance. By using radiolabeling and microautoradiography, it is proposed to examine more directly the interactions between light and gradients of photosynthetic performance within the leaf. These experiments will comprise a first step towards understanding the importance of leaf structure to photosynthetic performance in both agricultural and native species. ***