Leaf Structural Properties that Influence Internal Light Regime and Photosynthetic Efficiency: Epidermal Lens Cells and Internal Leaf Anatomy

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Photosynthesis is the process whereby plants convert solar energy into chemical energy. This process supports all life on this planet. An in depth knowledge of how photosynthesis occurs in leaves is necessary for understanding solar energy conversion by land plants. The project Leaf structural properties that influence internal light regime and photosynthetic efficiency: Epidermal lens cells and internal leaf anatomy will examine how leaf anatomy is related to the photosynthetic performance of the whole leaf. Specific native plants have been selected that have unique anatomical features. The purpose of the proposed research is to make correlations between the unique leaf anatomical features, the specialization of the photosynthetic apparatus within each leaf type, and whole leaf photosynthetic performance. One important leaf anatomical character that will be examined is the ability of the leaf epidermal cells to focus light within the leaf interior via a lens mechanism. Current research has shown that these cells can concentrate light 6-20 times above incident levels. Moreover, this epidermal lens action appears to strongly affect light-harvesting by the chloroplasts located within the leaf. Microscopy, gas exchange measurements and a new fiber optic microprobe technique will be used to accomplish the objectives of this project. The resulting information may be applied to problems that relate to understanding the physiological basis for plant biodiversity, increasing crop yield, and how plants may respond photosynthetically to global climate change mediated by increased carbon dioxide concentrations.