BTE endophytes

Fungal endophytes are an integral part of the leaf microbiome of forest trees. Most of these endophytes are horizontally transmitted, however little is known about their assembly drivers. Endophytic assemblages differ in composition according to geography and host individuals. In addition, climate and genetic diversity are also reported to lead to host plant adaptation. To determine the impact of the host progeny and respective adaptation to environmental conditions on endophytic assemblages, we designed a transplantation experiment in beech trees (Fagus sylvatica). Beech nuts were collected from distant geographical regions and germinated in a common greenhouse. One-year-old beech seedlings were transplanted to the different locations and the leaf-endophytic assemblages were characterized in the second growth season after planting by cultivation-independent metabarcoding. The chlorophyll and flavonoid content of the respective leaves were also measured. The results revealed host progeny effects in shaping leaf-endophytic fungal assemblages, that might be concealed by major geographical effects. We hypothesise and discuss possible interactions of different assembly drivers.

真菌内生菌（fungal endophytes）是林木叶片微生物组（leaf microbiome）的核心组成部分。这类内生菌大多通过水平传播，但目前对其群落构建的驱动因子仍知之甚少。内生真菌群落的组成会随地理区域与宿主个体的差异而有所不同。此外，已有研究表明气候与遗传多样性可推动宿主植物的适应性演化。为探究宿主子代及其对环境的适应性对内生真菌群落的影响，我们以欧洲山毛榉（Fagus sylvatica）为研究对象开展移植实验：从不同偏远地理区域采集山毛榉坚果，于统一温室中萌发培育；将生长满一年的山毛榉幼苗移植至多个试验点位，并在定植后的第二个生长季，通过非培养依赖型元条形码测序（metabarcoding）技术对其叶片内生真菌群落进行表征分析，同时测定对应叶片的叶绿素与类黄酮含量。研究结果显示，宿主子代对叶片内生真菌群落的构建存在调控作用，不过该效应可能被主要的地理因素所掩盖。我们针对不同群落构建驱动因子间的潜在相互作用提出假说并展开讨论。