Arbuscular mycorrhizal fungi mediate herbivore-induction of plant defenses differently above and belowground

Plants are exposed to herbivores and symbionts above and belowground. Herbivores aboveground alter plant defenses in both leaves and roots, affecting plant-herbivore interactions above and belowground. Root symbionts, such as arbuscular mycorrhizal fungi (AMF), also influence the defenses of leaves and roots, and alter plant responses to herbivory. However, we lack an understanding of how AMF mediate plant responses to herbivores simultaneously in above and belowground plant tissues, despite the ubiquity of such interactions and their consequences for ecological communities. In a full factorial experiment, we subjected plants of four milkweed (Asclepias) species under three levels of AMF inoculum availability to damage by aphids (Aphis nerii), caterpillars (Danaus plexippus), or no herbivores. We then measured foliar and root cardenolides (chemical defenses), leaf toughness, latex exudation (physical defenses), foliar carbon, nitrogen, and phosphorous concentrations, plant biomass, and ...

植物会同时暴露于地上与地下的植食性动物与共生体中。地上植食性动物可改变叶片与根系的植物防御机制，进而调控地上与地下的植物-植食动物互作。根系共生体，例如丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF），同样会调控叶片与根系的防御能力，并改变植物对植食作用的响应。然而，尽管这类互作广泛存在且会对生态群落产生诸多影响，我们仍未明确丛枝菌根真菌如何同时介导植物在地上与地下组织中对植食性动物的响应。本研究采用全因子实验设计，将4种马利筋属（Asclepias）植物置于3个丛枝菌根真菌接种量水平下，分别施加夹竹桃蚜（Aphis nerii）、帝王蝶（Danaus plexippus）取食处理，或不设置植食压力。随后我们测定了叶与根中的强心苷（化学防御物质）、叶片韧性、乳汁分泌量（物理防御指标），以及叶片碳、氮、磷浓度、植物生物量，以及……