Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA,
Oecologia. 2014 May;175(1):285-91. doi: 10.1007/s00442-014-2891-0. Epub 2014 Feb 2.
Endophytic plant symbionts can have powerful effects on the way their hosts interact with pathogens, competitors, and consumers. The presence of endophytes in plants can alter food webs, community composition and ecosystem processes, suggesting that endophyte-plant symbioses may represent unique forms of extended phenotypes. We tested the impact of the fungal endophyte Alternaria alternata (phylotype CID 120) on the allelopathic effect of the invasive forb Centaurea stoebe when in competition with the North American native bunchgrass Koeleria macrantha in a greenhouse competition experiment. The allelopathic effect of C. stoebe on K. macrantha when infected with the fungal endophyte was more than twice that of endophyte-free C. stoebe. However, this allelopathic effect was a small part of the very large competitive effect of C. stoebe on K. macrantha in all treatments, likely because of the priority effects in our experimental design. To our knowledge, these results are the first experimental evidence for a symbiotic relationship between plants and fungal endophytes affecting allelopathic interactions between competing plants, and thus provide insight into the mechanisms by which fungal endophytes may increase the competitive ability of their hosts.
内生植物共生体可以对宿主与病原体、竞争者和消费者的相互作用方式产生强大影响。植物内生菌的存在可以改变食物网、群落组成和生态系统过程，这表明内生菌-植物共生关系可能代表独特的扩展表型形式。我们在温室竞争实验中测试了真菌内生菌Alternaria alternata（phylotype CID 120）对入侵杂草矢车菊（Centaurea stoebe）与北美本地丛生草糙隐子草（Koeleria macrantha）竞争时的化感作用的影响。当真菌感染内生菌时，矢车菊对糙隐子草的化感作用是没有内生菌的矢车菊的两倍多。然而，在所有处理中，这种化感作用只是矢车菊对糙隐子草非常大的竞争作用的一小部分，这可能是由于我们实验设计中的优先效应。据我们所知，这些结果是植物和真菌内生菌之间共生关系影响竞争植物之间化感相互作用的第一个实验证据，因此为真菌内生菌如何提高宿主的竞争能力提供了一些见解。
