McCall Andrew C, Karban Richard
Center for Population Biology, Department of Entomology, University of California, Davis, CA, 95616, USA.
Oecologia. 2006 Jan;146(4):566-71. doi: 10.1007/s00442-005-0284-0. Epub 2005 Dec 3.
Plants protect themselves against herbivory using a continuum of strategies, ranging from constitutive defenses to intermittent induced responses. Induced defenses may not provide immediate and maximum protection, but could be advantageous when continuous defense is either energetically or ecologically costly. As such, induced defenses in flowers could help defend relatively valuable tissue while keeping reproductive structures accessible and attractive to pollinators. Thus far, no one has demonstrated the efficacy of induced defenses against floral herbivores (florivores) in the field. Here we show that mechanical leaf damage in wild tobacco, Nicotiana attenuata (Solanaceae), reduced both flower and fruit herbivory in the field and that exogenous application of methyl jasmonate, a potent elicitor of induced responses, reduced both leaf and floral damage in natural populations. This result is consistent with a survey of damage in the field, which showed a negative relationship between leaf damage and flower and fruit damage. Although optimal defense theory predicts that induced defenses should be rare in reproductive tissues, owing to their high fitness value, our results suggest otherwise. Induced defenses in leaves and reproductive tissues may allow plants to respond effectively to the concomitant pressures of defending against herbivory and attracting pollinators.
植物利用一系列策略来保护自己免受食草动物的侵害，从组成型防御到间歇性诱导反应。诱导防御可能无法提供即时和最大程度的保护，但当持续防御在能量或生态方面成本过高时，它可能具有优势。因此，花朵中的诱导防御可以帮助保护相对有价值的组织，同时使生殖结构对传粉者来说易于接近且具有吸引力。到目前为止，还没有人在田间证明诱导防御对花卉食草动物（食花动物）的有效性。在这里，我们表明，野生烟草（茄科烟草属）叶片的机械损伤减少了田间花朵和果实的食草动物侵害，并且外源施用茉莉酸甲酯（一种诱导反应的有效激发子）减少了自然种群中叶片和花朵的损伤。这一结果与田间损伤调查一致，该调查显示叶片损伤与花朵和果实损伤之间存在负相关关系。尽管最优防御理论预测，由于生殖组织具有很高的适合度价值，诱导防御在其中应该很少见，但我们的结果却并非如此。叶片和生殖组织中的诱导防御可能使植物能够有效应对抵御食草动物和吸引传粉者这两种伴随压力。
