Whose Phenotype is it Anyway? The Complex Role of Mycorrhizal Fungi in the Expression of Plant Defense

世界各地的植物必须保护自己免受包括昆虫、鹿和病原体在内的敌人的破坏。植物防御的范围从物理防御，如刺、刺和坚韧的叶子，到化学防御，如氰化物和类固醇。当植物试图自卫时，它们中的大多数都会利用生活在它们根部的真菌(称为菌根)提供给它们的营养。在基本上以物易物的系统中，植物为真菌提供糖，而真菌为植物提供磷等矿物质。植物的防御强度可能会随着根部真菌的数量和真菌伙伴的身份而变化，但这一点从未被详细研究过。本研究以普通乳草为研究对象，探索了植物防御强度如何随着真菌在根部的定植而变化。它考察了植物和真菌特性的变化如何有助于防御，以及土壤养分的自然变化如何影响易货系统。实验还探索了根部真菌对昆虫食草动物的影响。这项工作的结果将有助于理解从农作物到林木的各种植物物种如何在它们的防御策略中使用根部真菌。有可能操纵根部真菌来保护对人类很重要的植物，或者使那些入侵的害虫变得毫无防御能力。这项研究还将有助于在大学和当地学校培养下一代生物学家。

Plants worldwide must defend themselves from being damaged by their enemies, including insects, deer and pathogens. Plant defenses range from physical defenses, like thorns, spines, and tough leaves, to chemical defenses such as cyanide and steroids. As plants try to defend themselves, most of them make use of nutrients that are provided to them by fungi (called mycorrhizae) that live in their roots. In what is basically a barter system, plants provide the fungi with sugar while the fungi provide plants with minerals such as phosphorus. The strength of plant defenses may vary with the amount of fungus in their roots and the identity of their fungal partners, but this has never been studied in detail.Using common milkweed as a study plant, this research explores how the strength of plant defense varies with the fungal colonization of roots. It examines how variation in plant and fungal identity contributes to defense, and how natural variation in soil nutrients influences the barter system. Experiments also explore the effects of root fungi on insect herbivores. The results of this work will contribute to an understanding of how diverse plant species, from agricultural crops through forest trees, use root fungi in their defense strategies. It may be possible to manipulate root fungi to protect the plants that are important to humans or to render defenseless those that are invasive pests. The research will also help to train the next generation of biologists both in universities and in local area schools.