title: The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model.
abstract: Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm. We studied the influence of leaf anatomy and ambient light on internal light conditions and J The results show that (i) different chloroplasts can experience drastically different light conditions, even when they are located at the same distance from the leaf surface; (ii) bundle sheath extensions, which are strips of parenchyma, collenchyma or sclerenchyma cells connecting the vascular bundles with the epidermis, can influence photosynthetic light-use efficiency of leaves; and (iii) chloroplast positioning can also influence the light-use efficiency of leaves. Mechanisms underlying leaf internal light heterogeneity and implications of the heterogeneity for photoprotection and for the convexity of the light response curves are discussed.
authors.affiliation: CAS Key Laboratory of Computational Biology and State Key Laboratory of Hybrid Rice, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.|University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Institute of Botany, Department of Integrative Biology, University of Natural Resources and Applied Life Sciences, BOKU Vienna, Gregor Mendel-Str. 33, A-1180 Vienna, Austria.
authors.forename: Danny
authors.initials: D
authors.lastname: Tholen
authors.affiliation: CAS Key Laboratory of Computational Biology and State Key Laboratory of Hybrid Rice, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China zhuxinguang@picb.ac.cn.
authors.forename: Xin-Guang
authors.initials: XG
authors.lastname: Zhu
mesh_terms: D002473:Cell Wall / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology*; D008027:Light; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
keywords: Convexity; detour effect; focusing effect; leaf anatomy; photoinhibition; ray tracing model; sieve effect.