Environmental filtering structures fungal endophyte communities in tree bark

Area of Science:

• Plant-microbiome interactions
• Fungal community ecology
• Forest ecology

Background:

• Endophyte communities in inner tree bark are poorly understood.
• The role of bark in structuring these communities is debated: environmental filter vs. passive reservoir.

Purpose of the Study:

• To investigate if tree bark species act as environmental filters for endophyte communities.
• To characterize fungal communities within the inner bark of five dominant tree species.
• To determine the influence of bark chemistry on fungal community composition.

Main Methods:

• Developed a novel DNA extraction method for surface-sterilized inner bark.
• Conducted a culture-independent study on 120 trees across five species in a temperate forest.
• Analyzed fungal communities using DNA sequencing and correlated with bark chemical properties (pH, phenolics).

Main Results:

• Each tree species harbored distinct inner bark fungal communities.
• Angiosperm and gymnosperm hosts showed significantly different fungal assemblages.
• Bark chemical components (pH, phenolics) influenced fungal community structure.
• Inner bark fungal communities were highly diverse (117-171 OTUs/tree), dominated by Ascomycetes.

Conclusions:

• Tree bark acts as an environmental filter, actively structuring inner bark fungal communities.
• These findings support a role for plant-specific fungal communities in the plant microbiome.
• Further research is needed to understand the ecological significance of these endophytes.