Department of Biology, University of Konstanz, 78457, Constance, Germany.
Plant Ecophysiology, Department of Biology, Zukunftskolleg, University of Konstanz, 78457, Constance, Germany.
Plant Cell Environ. 2018 Jul;41(7):1683-1697. doi: 10.1111/pce.13213. Epub 2018 May 23.
Morphology, anatomy and physiology of sun and shade leaves of Abies alba were investigated and major differences were identified, such as sun leaves being larger, containing a hypodermis and palisade parenchyma as well as possessing more stomata, while shade leaves exhibit a distinct leaf dimorphism. The large size of sun leaves and their arrangement crowded on the upper side of a plagiotropic shoot leads to self-shading which is explainable as protection from high solar radiation and to reduce the transpiration via the lamina. Sun leaves furthermore contain a higher xanthophyll cycle pigment amount and Non-Photochemical Quenching (NPQ) capacity, a lower amount of chlorophyll b and a total lower chlorophyll amount per leaf, as well as an increased electron transport rate and an increased photosynthesis light saturation intensity. However, sun leaves switch on their NPQ capacity at rather low light intensities, as exemplified by several parameters newly measured for conifers. Our holistic approach extends previous findings about sun and shade leaves in conifers and demonstrates that both leaf types of A. alba show structural and physiological remarkable similarities to their respective counterparts in angiosperms, but also possess unique characteristics allowing them to cope efficiently with their environmental constraints.
对白桦阳叶和阴叶的形态、解剖和生理学进行了研究，发现了一些主要差异，如阳叶较大，含有下皮层和栅栏组织，并且具有更多的气孔，而阴叶表现出明显的叶二型性。阳叶的大型尺寸及其在偏上位置的密集排列导致了自遮蔽，这可以解释为对高太阳辐射的保护，并通过叶片减少蒸腾。此外，阳叶含有更高的叶黄素循环色素含量和非光化学猝灭（NPQ）能力，较少的叶绿素 b 和每片叶子的总叶绿素含量较低，以及增加的电子传递速率和增加的光合作用光饱和强度。然而，阳叶在相当低的光强度下就启动了它们的 NPQ 能力，这可以从几种新测量的针叶树参数中得到证明。我们的整体方法扩展了以前关于针叶树中阳叶和阴叶的发现，并表明 A. alba 的两种叶片类型都表现出与被子植物相应叶片类型结构和生理上显著的相似性，但也具有独特的特征，使它们能够有效地应对环境限制。
