Vertically transmitted fungal endophytes are common defensive symbionts of cool-season grasses. Protection against herbivores has been generally associated with alkaloids produced in the grass-endophyte symbiosis. However, many other changes occur in host metabolism like the release of VOCs. We aimed at characterizing the profile of volatile organic compounds (VOCs) induced by simultaneous fungal endophyte symbiosis and defoliation during the entire life cycle of the annual host grass and the asexual symbiont. We designed an outdoor factorial experiment with plots dominated by intact and damaged Lolium multiflorum plants with high and low infection levels with Epichloë occultans. After exploring the entire VOC profile, the green leaf volatile (Z)-3-hexenyl acetate (Z3-HAC) was found as the main compound emitted by the plants under field conditions. While in low-infected patches there were no differences in volatile emission during the plant life cycle, highly infected patches emitted more Z3-HAC in seedling and vegetative phases than in the reproductive phase. The role of Z3-HAC provided by symbiotic to neighbouring non-symbiotic plants in the associational protection against herbivores and fungal pathogens is discussed.

垂直传播的真菌内生菌是凉季草的常见防御共生体。食草动物的保护通常与草-内生菌共生中产生的生物碱有关。但是，宿主代谢中还会发生许多其他变化，例如VOC的释放。我们旨在表征在一年生寄主草和无性生物共生的整个生命周期中，真菌内生菌共生和脱叶同时引起的挥发性有机化合物（VOC）的特征。我们设计了一个户外因子分析实验，该实验以完整和受损的黑麦草植物为主导的地块，高和低水平的水生Epichloëoccultans感染。在探索了整个VOC曲线后，发现绿叶挥发物（Z）-3-己烯基乙酸酯（Z3-HAC）是植物在田间条件下排放的主要化合物。在低感染斑块中，在植物生命周期中挥发物的排放没有差异，而高感染斑块在幼苗期和营养期比繁殖期释放出更多的Z3-HAC。讨论了由共生物提供给邻近的非共生植物的Z3-HAC在对抗食草动物和真菌病原体的联合保护中的作用。