Cost of glandular trichomes, a "resistance" character in Datura wrightii Regel (Solanaceae)
Cost of glandular trichomes, a "resistance" character in Datura wrightii Regel (Solanaceae)
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DOI：
10.1111/j.1558-5646.1999.tb05330.x
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发表时间：
1999-02-01
期刊：
影响因子：
3.3
通讯作者：
Hare, JD
中科院分区：
文献类型：
--
作者：
Elle, E;van Dam, NM;Hare, JD
关于植物对食草动物抗性进化的模型通常假设维持抗性多态性的主要机制是增加对食草动物的抗性的益处和与产生抗性性状相关的成本之间的平衡。然而，很少有证据表明，基于遗传的抗性性状是昂贵的。在这里，我们记录的成本与腺毛的生产，主要是在一个单一的基因的控制下，大的影响，在曼陀罗wrightii的抗性字符。在没有食草动物的情况下，具有腺毛（粘性）的植物比具有非腺毛（天鹅绒状）的植物少产生45%的可行种子。虽然这两种植物类型开花的频率相似，粘性植物成熟较少的胶囊和较少的种子发芽。在无食草动物的条件下的类型之间的健身差异并没有减轻通过添加水，粘性植物的潜在限制资源。在食草压力下，绒状植物的适合度仍高于粘性植物，但各类型之间的适合度差异不显著。这发生在即使天鹅绒植物持续更多的草食动物比粘性植物的损害，更有可能受到大多数草食动物物种的攻击。植物类型之间的适合度差异，特别是减少时，食草动物攻击的植物浇水，这表明粘性植物可能有更高的耐受性比天鹅绒植物的损害时，提供了潜在的限制资源。然而，在我们研究的第一年，粘性植物受到食草动物攻击时，保持健身赤字（尽管很小，不显著）表明与腺毛的生产没有净效益。这些结果增加了我们目前的理解，草食动物抗性字符可以是昂贵的，并提出了如何在野生种群中保持这种遗传多态性的问题。
Models regarding the evolution of plant resistance to herbivory often assume that the primary mechanism maintaining resistance polymorphisms is the balance between benefits of increased resistance to herbivores and costs associated with the production of a resistance character. However, rarely has it been demonstrated that genetically based resistance traits are costly. Here, we document costs associated with the production of glandular trichomes, a resistance character in Datura wrightii that is predominantly under the control of a single gene of large effect. In the absence of herbivores, plants with glandular trichomes (sticky) produced 45% fewer viable seeds than plants with nonglandular trichomes (velvety). Although both plant types flowered with similar frequency, sticky plants matured fewer capsules and fewer of their seeds germinated. The fitness difference between the types in herbivore-free conditions was not mitigated by the addition of water, a potentially limiting resource for sticky plants. Under herbivore pressure, there was no significant fitness difference between the types, although the fitness of velvety plants was still higher than that of sticky plants. This occurred even though velvety plants sustained more herbivore damage than sticky plants and were more likely to be attacked by most herbivore species present. The fitness difference between the plant types was especially reduced when herbivore-attacked plants were watered, which indicates that sticky plants may have higher tolerance for damage than velvety plants when supplied with a potentially limiting resource. Yet, the maintenance of a fitness deficit (albeit small and nonsignificant) for sticky plants when attacked by herbivores indicates no net benefit associated with the production of glandular trichomes in this first year of our study. These results add to our current understanding that herbivore resistance characters can be costly and raise the question of how this genetic polymorphism is maintained in wild populations.