Plant chemical defense against herbivores and pathogens: generalized defense or trade-offs?
Plant chemical defense against herbivores and pathogens: generalized defense or trade-offs?
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DOI：
10.1007/s00442-004-1603-6
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发表时间：
2004-08-01
期刊：
影响因子：
2.7
通讯作者：
van Damme, JMM
中科院分区：
文献类型：
--
作者：
Biere, A;Marak, HB;van Damme, JMM
植物经常受到多种敌人的攻击，包括病原体和食草动物。虽然许多植物次生代谢产物对病原体或食草动物表现出特定的作用，但有些次生代谢产物可以影响这两类天敌的表现，并被认为是“广义防御化合物”。我们测试了桃叶珊瑚苷和梓醇，两个环烯醚萜苷存在于车前（车前），赋予在体内抗性的通性昆虫食草动物甜菜夜蛾和活体营养型真菌病原体Diaporthe adunca使用植物从车前线，已选择高和低叶环烯醚萜苷浓度四代。这些品系在这些化合物的水平上相差约三倍。来自高选择系的植株表现出增强的对S. exigua和D. adunca，如由较小的病变大小和较低的真菌生长速率和孢子产生，以及较低的幼虫生长速率和草食性在选择和无选择条件下所证明的。重量分析表明，环烯醚萜苷类化合物对S.甜菜，从而降低其食物摄入率，而不是具有消化后毒性作用，如从水解产物的体外作用预测的。我们认为，苦味的环烯醚萜苷阻止摄食的S。甜菜根，而真菌感染后的组织损伤后形成的水解产物介导病原体抗性。我们的结论是，环烯醚萜苷在披针叶可以作为广谱防御和病原体抗性的选择可能会导致增加抗性的通才昆虫食草动物，反之亦然，导致扩散，而不是成对的共同进化。
Plants are often attacked by multiple enemies, including pathogens and herbivores. While many plant secondary metabolites show specific effects toward either pathogens or herbivores, some can affect the performance of both these groups of natural enemies and are considered to be "generalized defense compounds". We tested whether aucubin and catalpol, two iridoid glycosides present in ribwort plantain (Plantago lanceolata), confer in vivo resistance to both the generalist insect herbivore Spodoptera exigua and the biotrophic fungal pathogen Diaporthe adunca using plants from P. lanceolata lines that had been selected for high- and low-leaf iridoid glycoside concentrations for four generations. The lines differed approximately three-fold in the levels of these compounds. Plants from the high-selection line showed enhanced resistance to both S. exigua and D. adunca, as evidenced by a smaller lesion size and a lower fungal growth rate and spore production, and a lower larval growth rate and herbivory under both choice and no-choice conditions. Gravimetric analysis revealed that the iridoid glycosides acted as feeding deterrents to S. exigua, thereby reducing its food intake rate, rather than having post-ingestive toxic effects as predicted from in vitro effects of hydrolysis products. We suggest that the bitter taste of iridoid glycosides deters feeding by S. exigua, whereas the hydrolysis products formed after tissue damage following fungal infection mediate pathogen resistance. We conclude that iridoid glycosides in P. lanceolata can serve as broad-spectrum defenses and that selection for pathogen resistance could potentially result in increased resistance to generalist insect herbivores and vice versa, resulting in diffuse rather than pairwise coevolution.