Gilbert Gregory S, Parker Ingrid M
Environmental Studies Department, University of California Santa Cruz, CA, USA.
Ecology and Evolutionary Biology, University of California Santa Cruz, CA, USA.
Evol Appl. 2010 Mar;3(2):144-56. doi: 10.1111/j.1752-4571.2009.00107.x.
Plant species introduced into new regions can both leave behind co-evolved pathogens and acquire new ones. Traits important to infection and virulence are subject to rapid evolutionary change in both plant and pathogen. Using Stemphylium solani, a native foliar necrotroph on clovers (Trifolium and Medicago) in California, USA, we explore how plant-fungal interactions may change in an invasion context. After four generations of experimental serial passage through multiple hosts, Stemphylium consistently showed increased infection rates but no consistent change in damage to the host. In a historical opportunity study, we compared infection and virulence across four groups of clover hosts: California natives, European clovers not found in California, and both California and European genotypes of species naturalized in California. There was significant variation among hosts, but no pattern across the four groups. However, in direct comparisons of familiar California genotypes to unfamiliar European genotypes of the same naturalized species, Stemphylium consistently infected familiar hosts more frequently, while causing less damage on them. This pattern is consistent with the hypothesis of adaptive evolution in both the pathogen (ability to infect) and the host (tolerance of infection). Together these results suggest the potential for rapid evolution to alter interactions between plant invaders and their natural enemies.
引入新区域的植物物种既可能遗留共同进化的病原体，也可能获得新的病原体。对感染和毒力至关重要的性状在植物和病原体中都会经历快速的进化变化。我们以茄匐柄霉为例进行研究，它是美国加利福尼亚州三叶草（车轴草属和苜蓿属）上的一种本土叶部坏死营养型真菌，探讨在入侵背景下植物与真菌的相互作用可能如何变化。经过在多个宿主上连续四代的实验传代后，茄匐柄霉始终表现出感染率增加，但对宿主的损害没有一致的变化。在一项历史机遇研究中，我们比较了四组三叶草宿主的感染情况和毒力：加利福尼亚本土品种、在加利福尼亚未发现的欧洲三叶草品种，以及在加利福尼亚归化的物种的加利福尼亚和欧洲基因型。宿主之间存在显著差异，但四组之间没有规律。然而，在将熟悉的加利福尼亚基因型与同一归化物种的不熟悉的欧洲基因型进行直接比较时，茄匐柄霉始终更频繁地感染熟悉的宿主，同时对它们造成的损害更小。这种模式与病原体（感染能力）和宿主（对感染的耐受性）适应性进化的假设一致。这些结果共同表明，快速进化有可能改变植物入侵者与其天敌之间的相互作用。
