Delaney Kevin J, Higley Leon G
Department of Entomology, University of Nebraska-Lincoln, 202 Plant Industry Building, Lincoln, NE 68583-0816, USA.
Plant Cell Environ. 2006 Jul;29(7):1245-58. doi: 10.1111/j.1365-3040.2006.01504.x.
One type of specialised herbivory receiving little study even though its importance has frequently been mentioned is vein cutting. We examined how injury to a leaf's midrib vein impairs gas exchange, whether impairment occurs downstream or upstream from injury, duration of impairment, compared the severity of midrib injury with non-midrib defoliation, and modelled how these two leaf injuries affect whole-leaf photosynthesis. Leaf gas exchange response to midrib injury was measured in five Asclepiadaceae (milkweed), one Apocynaceae (dogbane), one Polygonaceae and one Fabaceae species, which have been observed or reported to have midrib vein cutting injury in their habitats. Midrib vein injury impaired several leaf gas exchange parameters, but only downstream (distal) from the injury location. The degree of gas exchange impairment from midrib injury was usually more severe than from manually imposed and actual insect defoliation (non-midrib), where partial recovery occurred after 28 d in one milkweed species. Non-midrib tissue defoliation reduced whole-leaf photosynthetic activity mostly by removing photosynthetically active tissue, while midrib injury was most severe as the injury location came closer to the petiole. Midrib vein cutting has been suggested to have evolved as a countermeasure to deactivate induced leaf latex or cardenolide defences of milkweeds and dogbanes, yet vein cutting effects on leaf physiology seem more severe than the non-midrib defoliation the defences evolved to deter.
有一种专门的食草行为，尽管其重要性经常被提及，但却很少有人研究，这就是叶脉切割。我们研究了叶片中脉受损如何影响气体交换，这种损害是发生在损伤部位的下游还是上游，损害的持续时间，将中脉损伤的严重程度与非中脉落叶进行比较，并建立模型来研究这两种叶片损伤如何影响整叶光合作用。在五种萝摩科（马利筋）、一种夹竹桃科（罗布麻）、一种蓼科和一种豆科植物中测量了叶片气体交换对中脉损伤的反应，这些植物在其栖息地已被观察到或报道有中脉切割损伤。中脉损伤损害了几个叶片气体交换参数，但仅在损伤部位的下游（远端）。中脉损伤导致的气体交换损害程度通常比人工造成的和实际昆虫造成的落叶（非中脉）更严重，在一种马利筋中，28天后部分恢复。非中脉组织落叶主要通过去除光合活性组织来降低整叶光合活性，而中脉损伤随着损伤部位靠近叶柄而最为严重。有人认为叶脉切割是作为一种对策而进化出来的，用于使马利筋和罗布麻诱导产生的叶乳胶或强心甾防御失活，然而叶脉切割对叶片生理的影响似乎比这些防御所进化来阻止的非中脉落叶更为严重。
