PDF(Pubmed)
Abstract：
The differential effects of cellular and ultrastructural characteristics on the optical properties of adaxial and abaxial leaf surfaces in the genus Tradescantia highlight the intricate relationships between cellular arrangement and pigment distribution in the plant cells. We examined hyperspectral and chlorophyll a fluorescence (ChlF) kinetics using spectroradiometers and optical and electron microscopy techniques. The leaves were analysed for their spectral properties and cellular makeup. The biochemical compounds were measured and correlated with the biophysical and ultrastructural features. The main findings showed that the top and bottom leaf surfaces had different amounts and patterns of pigments, especially anthocyanins, flavonoids, total phenolics, chlorophyll-carotenoids, and cell and organelle structures, as revealed by the hyperspectral vegetation index (HVI). These differences were further elucidated by the correlation coefficients, which influence the optical signatures of the leaves. Additionally, ChlF kinetics varied between leaf surfaces, correlating with VIS-NIR-SWIR bands through distinct cellular structures and pigment concentrations in the hypodermis cells. We confirmed that the unique optical properties of each leaf surface arise not only from pigmentation but also from complex cellular arrangements and structural adaptations. Some of the factors that affect how leaves reflect light are the arrangement of chloroplasts, thylakoid membranes, vacuoles, and the relative size of the cells themselves. These findings improve our knowledge of the biophysical and biochemical reasons for leaf optical diversity, and indicate possible implications for photosynthetic efficiency and stress adaptation under different environmental conditions in the mesophyll cells of Tradescantia plants.
摘要：
细胞和超微结构特征对紫草属植物正面和背面叶表面光学特性的不同影响突出了植物细胞中细胞排列与色素分布之间的复杂关系。我们使用光谱辐射计以及光学和电子显微镜技术检查了高光谱和叶绿素a荧光（ChlF）动力学。分析叶子的光谱特性和细胞组成。测量了生化化合物，并将其与生物物理和超微结构特征相关联。主要研究结果表明,上、下叶面有不同数量和形态的色素,尤其是花青素,黄酮类化合物，总酚类物质，叶绿素类胡萝卜素，细胞和细胞器结构，正如高光谱植被指数(HVI)所揭示的。这些差异由相关系数进一步阐明，影响叶子的光学特征。此外,ChlF动力学在叶片表面之间变化，通过皮下细胞中不同的细胞结构和色素浓度与VIS-NIR-SWIR谱带相关。我们证实，每个叶片表面的独特光学特性不仅来自色素沉着，而且还来自复杂的细胞排列和结构适应。影响树叶反射光的一些因素是叶绿体的排列，类囊体膜,空泡,以及细胞本身的相对大小。这些发现提高了我们对叶片光学多样性的生物物理和生化原因的认识，并指出在不同环境条件下，紫草属植物叶肉细胞的光合效率和胁迫适应可能的意义。
