RUI: Mediation of Induced Resistance to Insects by a Fungal Endophyte

9527749 Bultman内生真菌的存在通常与宿主草的生存和繁殖增强有关。 由于食草昆虫对被真菌感染的草造成的损害往往比缺乏真菌伴生物的草小，草-真菌伴生物被描述为防御性互惠共生。 这种防御的假设机制可能是真菌产生的生物碱，对昆虫有毒。 拟议的研究专门测试内生菌感染草的优势是否是由于植物受损后对昆虫的抵抗力增强。 操纵营养水平，植物损害和真菌感染的实验室实验将进行使用咀嚼，硬，高羊茅和多年生黑麦草。 植物组织将被喂养到秋天和真正的粘虫幼虫和他们的生长和生存监测，以评估在真菌感染和无真菌植物的基础水平和伤口诱导的电阻的存在和幅度。 还将监测植物蛋白氮和生物碱的水平，以帮助解释实验处理之间昆虫表现的差异。 将评估两种昆虫食草动物的生物量增加和消耗，以进一步评价处理对昆虫性能影响的机制。 禾本科植物内生真菌的经济意义是有据可查的。 真菌及其产生的毒素对牲畜产生有害影响，导致美国每年损失超过6亿美元的收入。 拟议中的研究，通过提供有关草内生菌的基本生态学的信息，应有助于在农业环境中管理它们。

9527749 Bultman The presence of an endophytic fungus is often associated with enhanced survival and reproduction of the host grass. Because insect herbivores often cause less damage to grasses infected by the fungi compared to grasses lacking the fungal associates, the grass-fungus association has been described as a defensive mutualism. A hypothesized mechanism for this defense may be fungal-produced alkaloids that can be toxic to insects. The proposed study specifically tests if the advantage of endophyte infection to grasses is due to enhanced resistance to insects following plant damage. Laboratory experiments manipulating nutrient levels, plant damage, and fungal infection will be conducted using Chewings, hard, and tall fescues and perennial ryegrass. Plant tissue will be fed to fall and true armyworm larvae and their growth and survival monitored to assess the presence and magnitude of base level and wound-induced resistance in fungal-infected and fungal-free plants. The level of plant protein nitrogen and alkaloids will also be monitored to help interpret differences in insect performance among experimental treatments. Biomass gain and consumption of the two insect herbivores will be assessed to further evaluate mechanisms responsible for treatment effects on insect performance. The economic significance of fungal endophytes of grasses is well documented. The fungi, and the toxins they produce, have detrimental effects on livestock that translate to annual revenue losses of over $600 million in the US. The proposed research, by providing information on the basic ecology of grass endophytes, should assist efforts to manage them in agricultural settings.