Foliar phosphorus concentration modulates the defensive mutualism of an endophytic fungus in a perennial host grass

Grasses hosting Epichloë endophytes are protected against herbivores due to the production of various fungal alkaloids. Previous research has found that high foliar phosphorus concentrations reduce the level of the alkaloid ergovaline, thereby reducing the endophyte-mediated herbivore resistance. Yet, the impact of phosphorus on ergovaline biosynthesis versus its influence on endophyte growth and synthesis of other fungal alkaloids remains unresolved. Our objective was to elucidate these relationships. We grew endophyte-symbiotic and non-symbiotic Festuca arundinacea plants and fertilized them with different doses of phosphorus. Later, half of the plants from each treatment were challenged with larvae of the generalist chewing insect Spodoptera frugiperda. We assessed the relationships between foliar phosphorus levels, fungal mycelium, and alkaloid concentrations, as well as their impacts on larvae performance, herbivore-caused damage, and plant biomass. Endophyte mycelial biomass in pl..., Herbivory index We used an herbivory index to estimate the damage caused by herbivores to plants (Boege & Dirzo, 2004; Salgado-Luarte et al., 2023). Plants not exposed to herbivores were not included in this calculation as they did not show signs of damage (personal observation). For each estimation, five leaves were randomly selected and photographed. Then, the damaged area was estimated using the software ImageJ (Abrà moff et al., 2004). As in Boege & Dirzo (2004), each leaf was scored according to the level of damage: 0 = no damage, 1 = 1-6% damage, 2 = 6-12% damage, 3 = 12-25% damage, 4 = 25-50% damage, and 5 = more than 75% of damage. These categories were selected because low levels of damage were most frequent and high levels of damage were less common. Thus, categories with narrower ranges were needed in the lower part of the range to capture differences in plant damage (Boege & Dirzo, 2004). Adapted from Boege and Dirzo (2004), the herbivory index for each plant was ..., , # Foliar phosphorus concentration modulates the defensive mutualism of an endophytic fungus in a perennial host grass [https://doi.org/10.5061/dryad.c2fqz61jd](https://doi.org/10.5061/dryad.c2fqz61jd) We conducted an experiment to study how phosphorus fertilization modulates the production of anti-herbivory alkaloids in grasses associated with Epichloë endophytes. We used *Lolium arundinaceum* plants, either associated with the fungal endophyte *Epichloë coenophiala* or not. The plants were treated with four different levels of phosphorus fertilization (no fertilization, low, medium, and high) and exposed half of the plants to larvae of the insect herbivore *Spodoptera frugiperda*. This repository contains the data produced by this experiment. ## Description of the data The data is contained in a single CSV file. Each column represents a factor or a variable, and each row contains data from an individual plant. ### Experimental factors * endo: *Epichloë* endophyte presence (E+) ...定植有香柱菌属（Epichloë）内生真菌的禾本科植物，可通过该真菌产生的多种生物碱获得抗草食动物侵害的能力。既往研究表明，植株叶片高磷浓度会降低生物碱麦角缬氨酸（ergovaline）的含量，进而削弱内生真菌介导的抗草食动物抗性。然而，磷对麦角缬氨酸生物合成的影响，及其对内生真菌生长与其他真菌生物碱合成的作用之间的关联仍未明确。本研究旨在阐明上述关联。我们培养了定植有内生真菌的和未定植的苇状羊茅（Festuca arundinacea）植株，并施加不同剂量的磷素肥料。随后，将各处理组中半数植株接种广食性咀嚼式昆虫草地贪夜蛾（Spodoptera frugiperda）的幼虫。我们评估了叶片磷素水平、真菌菌丝体与生物碱浓度之间的关联，以及这些因素对幼虫生长表现、草食动物造成的损害程度与植株生物量的影响。内生真菌菌丝生物量在……，草食为害指数 我们采用草食为害指数（herbivory index）评估草食动物对植株造成的损害程度（Boege & Dirzo, 2004; Salgado-Luarte et al., 2023）。未接触草食动物的植株因未表现出任何受害迹象，未纳入该计算（个人观测数据）。每次评估时，我们随机选取5片叶片并拍照，随后使用ImageJ软件（ImageJ）估算受害面积（Abràmoff et al., 2004）。参照Boege与Dirzo（2004）的方法，我们根据受害程度对每片叶片进行评分：0分表示无受害，1分表示受害面积1%-6%，2分表示6%-12%，3分表示12%-25%，4分表示25%-50%，5分表示受害面积超过75%。该评分分级的设置是因为低程度受害最为常见，而高程度受害则相对少见，因此在受害程度较低的区间设置更窄的分级范围，以更好地捕捉植株受害程度的差异（Boege & Dirzo, 2004）。改编自Boege与Dirzo（2004）的方法，单株草食为害指数为…… # 叶片磷浓度调控多年生宿主禾草与内生真菌的防御共生关系 [https://doi.org/10.5061/dryad.c2fqz61jd](https://doi.org/10.5061/dryad.c2fqz61jd) 本研究开展了一项实验，以探究磷素施肥如何调控与香柱菌属（Epichloë）内生真菌共生的禾本科植物的抗草食动物生物碱合成。我们选用了与内生真菌Epichloë coenophiala共生或未共生的苇状羊茅（*Lolium arundinaceum*）植株。对这些植株施加4个梯度的磷素施肥处理（不施肥、低剂量、中剂量与高剂量），并将各处理组中半数植株接种草食性昆虫草地贪夜蛾（Spodoptera frugiperda）幼虫。 本数据集包含本实验产生的全部数据。 ## 数据集说明 所有数据存储于单个CSV文件（CSV）中，每一列代表一个实验因子或变量，每一行对应一株单独的植株。 ### 实验因子 * endo：香柱菌属（Epichloë）内生真菌定植情况（E+ 表示定植，E- 表示未定植）……