Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark.
Oecologia. 2014 Jun;175(2):589-600. doi: 10.1007/s00442-014-2928-4. Epub 2014 Apr 1.
Plants are often attacked by pathogens and insects. Their combined impact on plant performance and fitness depends on complicated three-way interactions and the plant's ability to compensate for resource losses. Here, we evaluate the response of Barbarea vulgaris, a wild crucifer, to combined attack by an oomycete Albugo sp., a plant pathogen causing white rust, and a flea beetle, Phyllotreta nemorum. Plants from two B. vulgaris types that differ in resistance to P. nemorum were exposed to Albugo and P. nemorum alone and in combination and then monitored for pathogen infection, herbivore damage, defence compounds, nutritional quality, biomass and seed production. Albugo developed infections in the insect-resistant plants, whereas insect-susceptible plants were scarcely infected. Concentrations of Albugo DNA were higher in plants also exposed to herbivory; similarly, flea beetle larvae caused more damage on Albugo-infected plants. Concentrations of saponins and glucosinolates strongly increased when the plants were exposed to P. nemorum and when the insect-susceptible plants were exposed to Albugo, and some of these compounds increased even more in the combined treatment. The biomass of young insect-susceptible plants was lower following exposure to flea beetles, and the number of leaves of both plant types was negatively affected by combined exposure. After flowering, however, adult plants produced similar numbers of viable seeds, irrespective of treatment. Our findings support the concept that pathogens and herbivores can affect each other's performance on a host plant and that the plant reacts by inducing specific and general defences. However, plants may be able to compensate for biomass loss from single and combined attacks over time.
植物经常受到病原体和昆虫的攻击。它们对植物性能和适应性的综合影响取决于复杂的三方相互作用以及植物补偿资源损失的能力。在这里，我们评估了野生十字花科植物野菘 Barbarea vulgaris 对卵菌属 Albugo 种（引起白锈病的植物病原体）和叶甲 Phyllotreta nemorum（一种 flea beetle）联合攻击的反应。来自两种 B. vulgaris 类型的植物，它们对 P. nemorum 的抗性不同，分别单独和联合暴露于 Albugo 和 P. nemorum 后，监测病原体感染、食草动物损害、防御化合物、营养质量、生物量和种子产量。在抗虫植物中，Albugo 发生了感染，而对昆虫敏感的植物则很少被感染。暴露于食草动物的植物中 Albugo 的 DNA 浓度更高；同样，叶甲幼虫在感染 Albugo 的植物上造成的损害更大。当植物暴露于 P. nemorum 时，以及当易受昆虫侵害的植物暴露于 Albugo 时，皂甙和硫代葡萄糖苷的浓度强烈增加，在联合处理中，这些化合物中的一些甚至增加更多。易受昆虫侵害的年轻植物在暴露于叶甲后生物量较低，两种植物类型的叶片数量都受到联合暴露的负面影响。然而，开花后，成年植物产生了相似数量的有活力的种子，无论处理方式如何。我们的研究结果支持这样的概念，即病原体和食草动物可以相互影响宿主植物的性能，而植物通过诱导特定和一般防御来反应。然而，植物可能能够随着时间的推移补偿单一和联合攻击造成的生物量损失。
