Neotyphodium fungal endophytes are keystone species in temperate grasslands: impacts from population ecology to ecosystem functioning

北美各地使用的草坪草和草坪草大多是非本地物种。 这些草通常逃避人类的管理，侵入自然和未受管理的生态系统，在那里它们被广泛认为是重要的入侵物种。 当这些植物感染内生真菌时，这些草对它们入侵的生态系统的影响被认为更加显著。 农业和草坪草通常是系统性共生真菌内生菌的宿主，其驻留在气生植物部分中并且通过受感染的草的种子垂直传播。 理论表明，垂直传播的共生体必须以某种方式增强宿主植物的适应性，如果它们要在种群中维持的话。 内生菌感染被认为通过增加对非生物胁迫（例如干旱）的耐受性、增强的生长和竞争能力以及由于产生内生菌衍生的生物碱而增加的对草食动物的抗性而使其宿主草受益。 事实上，这最后一个好处导致许多人将这种互动描述为防御互利主义。 所有这些好处使得内生菌感染的草更有可能成功入侵自然群落，并且在入侵这些群落时产生更大的影响。

Pasture and turfgrasses used throughout North America are mostly non-native species. These grasses routinely escape their human management and invade natural and unmanaged ecosystems where they are widely considered to be significant invasive species. The impact that these grasses have on the ecosystems that they invade is thought to be more significant when those plants are infected with endophytic fungi. Agricultural and turfgrasses are often hosts of systemic symbiotic fungal endophytes which reside in aerial plant parts and are vertically transmitted through the seeds of infected grasses. Theory suggests that the vertically transmitted symbionts must, in some way, enhance the fitness of the host plant if they are to be maintained in the population. Endophyte infection is proposed to benefit their host grasses through increased tolerance to abiotic stress (e.g. drought), enhanced growth and competitive ability, and increased resistance to herbivory due to the production of endophyte-derived alkaloids. Indeed, this last benefit has led many to describe the interaction as a defense mutualism. All of these benefits make endophyte-infected grasses more likely to succeed in invading natural communities and to have greater impact when they do invade such communities.