School of Biological Sciences, Monash University, Victoria 3800, Australia.
Am J Bot. 2006 Oct;93(10):1531-45. doi: 10.3732/ajb.93.10.1531.
Terrestrial plant leaves are complex structures of composite materials. Resistance to fracture is achieved by a number of mechanisms, which operate at the molecular, cell, tissue, and structural levels. Leaves of dicots have different venation patterns and cell wall volume fractions from those of grasses, and consequently, they potentially resist fracture in different ways. Animals mechanically process plants in order to rupture the cell wall in preparation for enzymic hydrolysis, for which the imperative is to maximize new surface area and/or to expedite access to cell contents, ideally by promoting elastic fracture. The two different plant types are fed on by two different groups of organisms of very different sizes, digestive physiologies, mechanical processing abilities and properties, and nutritional requirements. Small insects can feed in or on parts of leaves, while larger mammals generally have to feed on the whole leaf. The scale of feeding also differs for the two groups of herbivores, but how this interacts with the scale of the mechanical properties of the leaf is not well understood. Plant leaves are attacked at all scales and probably can only produce generalized responses to specialized herbivores. In addition, the opportunities that these different scales of interactions open for the different herbivores remain unexplored.
陆生植物叶片是复合材料的复杂结构。通过多种机制来实现抗断裂性，这些机制在分子、细胞、组织和结构水平上起作用。双子叶植物的叶脉模式和细胞壁体积分数与禾本科植物不同，因此它们可能以不同的方式抵抗断裂。动物通过机械加工植物来破坏细胞壁，为酶解做准备，其关键是最大限度地增加新表面积和/或加快对细胞内容物的获取，理想情况下是通过促进弹性断裂来实现。这两种不同的植物类型被两类大小、消化生理、机械加工能力和特性以及营养需求都非常不同的生物所食用。小昆虫可以在叶片的内部或外部进食，而较大的哺乳动物通常只能吃整片叶子。这两组食草动物的摄食规模也不同，但这与叶片机械性能的规模如何相互作用尚不清楚。植物叶片在各个尺度上都受到攻击，可能只能对专门的食草动物产生一般性反应。此外，这些不同的相互作用尺度为不同的食草动物提供了机会，但这些机会仍未被探索。
