The taxonomically diverse phyllosphere fungi inhabit leaves of plants. Thus, apart from the fungi's dispersal capacities and environmental factors, the assembly of the phyllosphere community associated with a given host plant depends on factors encoded by the host's genome. The host genetic factors and their influence on the assembly of phyllosphere communities under natural conditions are poorly understood, especially in trees. Recent work indicates that Norway spruce (Picea abies) vegetative buds harbour active fungal communities, but these are hitherto largely uncharacterized. This study combines internal transcribed spacer sequencing of the fungal communities associated with dormant vegetative buds with a genome-wide association study (GWAS) in 478 unrelated Norway spruce trees. The aim was to detect host loci associated with variation in the fungal communities across the population, and to identify loci correlating with the presence of specific, latent, pathogens. The fungal communities were dominated by known Norway spruce phyllosphere endophytes and pathogens. We identified six quantitative trait loci (QTLs) associated with the relative abundance of the dominating taxa (i.e., top 1% most abundant taxa). Three additional QTLs associated with colonization by the spruce needle cast pathogen Lirula macrospora or the cherry spruce rust (Thekopsora areolata) in asymptomatic tissues were detected. The identification of the nine QTLs shows that the genetic variation in Norway spruce influences the fungal community in dormant buds and that mechanisms underlying the assembly of the communities and the colonization of latent pathogens in trees may be uncovered by combining molecular identification of fungi with GWAS.

中文翻译：

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挪威云杉的基因型变异与营养芽中的真菌群落相关。

分类学上多样化的叶圈真菌栖息在植物的叶子中。因此，除了真菌的传播能力和环境因素之外，与给定宿主植物相关的叶际群落的组装还取决于宿主基因组编码的因素。人们对自然条件下的宿主遗传因素及其对叶际群落组装的影响知之甚少，尤其是在树木中。最近的研究表明，挪威云杉（Picea abies）的营养芽中含有活跃的真菌群落，但迄今为止这些真菌群落在很大程度上还没有被表征。这项研究将与休眠营养芽相关的真菌群落的内部转录间隔区测序与对 478 棵不相关的挪威云杉树进行的全基因组关联研究 (GWAS) 结合起来。目的是检测与整个人群真菌群落变异相关的宿主位点，并识别与特定潜在病原体存在相关的位点。真菌群落以已知的挪威云杉叶际内生菌和病原体为主。我们确定了与主要类群（即前 1% 最丰富类群）相对丰度相关的 6 个数量性状基因座 (QTL)。在无症状组织中检测到了与云杉针铸病原体 Lirula macrospora 或樱桃云杉锈病 (Thekopsora areolata) 定植相关的另外 3 个 QTL。9个QTL的鉴定表明，挪威云杉的遗传变异影响休眠芽中的真菌群落，通过将真菌分子鉴定与GWAS相结合，可以揭示群落组装和潜在病原体在树木中定植的机制。