A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species.
A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species.
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DOI：
10.1093/jxb/erv024
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发表时间：
2015-05
影响因子：
6.9
通讯作者：
Anten NP
中科院分区：
文献类型：
--
作者：
Onoda Y;Schieving F;Anten NP
叶片层是在三明治结构中设计的，这是一种非常有效的结构，例如飞机翼，使叶子较薄，平坦，非常适合光合作用，但也可以机械稳定。
植物通常会暴露出薄的平坦结构，可促进每单位质量的高光拦截，但在受到重力，风和草食性以及其他应力时，可能会增加机械故障的风险。中叶层层，类似于复合材料，即三明治结构，用于工程结构（例如飞机机翼），其中高弯曲最小的刚度很重要。层。比表皮层低得多，表明叶片与有效的三明治结构相似。整个研究的物种都表明，三明治结构具有进化的优势，因为它使叶子简单稀薄，并且平坦，有效捕获光线并在各种应力下保持机械稳定性。
Leaf laminas are designed in sandwich structure, a very efficient structure used in e.g. airplane wing, which enables leaves to be thin, flat, ideal for photosynthesis but also mechanically stable. Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young’s moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses.