Abstract
Pinus koraiensis Sieb. et Zucc. is an endemic and dominant tree in temperate zone needle broad-leaf mixed forest and has great economic and ecological value. As the barrier, pine bark has many important functions. However, the ecological functions and forming mechanism of bark fungal community are poorly understood. The aim of this study was to reveal the fungal community of Korean pine bark from Changbai Nature Reserve of Northeast China. Based on Illumina Hiseq2000 platform with five different types from three sites, the results showed that the bark types and collecting sites have strong influence on the fungal community structure. CCA demonstrates the physico-chemical properties of barks and sample collecting height are important factors. Spearman’s correlation coefficients between dominant ASVs and these factors showed the impact in detail. Dominant ASVs in living and dead tree bark are animal or plant pathogens mainly, and they are negative with the total N and P. Meanwhile, wood saprotroph and other undefined saprotroph fungi occur in the bark near the ground and they prefer the substrate with higher total N and P content. Furthermore, enzymes activities including lignin-related oxidoreductases, cellulose and hydrolytic enzyme are affected significantly by the bark’s physico-chemical properties.
Highlights
Deadwood is known to be an important structural component of forests by representing a key processes in the carbon and nitrogen cycle and contributes to the soil forming processes and provides habitats as well as carbon and energy sources for a diverse range of forest species
2264 amplicon sequence variants (ASVs) were annotated about ecological function of bark samples and 4413 ASVs were annotated about ecological function of soil samples
Comparing extracellular enzyme distribution in five types of bark, the results showed that the highest activity of the hydrolytic enzyme β-1,4-xylosidase and cellobiohydrolase were present in type IV pine bark, and the activity of cellulose enzyme endo-1,4-β-xylanase in it was the highest
Summary
Deadwood is known to be an important structural component of forests by representing a key processes in the carbon and nitrogen cycle and contributes to the soil forming processes and provides habitats as well as carbon and energy sources for a diverse range of forest species. Wood mainly consists of cellulose and hemicelluloses incrusted with lignin, which protects the polysaccharides from microbial decomposition [1]. Wooddecaying fungi belonging to the Basidiomycota and few Ascomycota can attack and destroy the lignin-barrier, playing a key ecological function during the wood-degrading process. These fungi are capable of degrading lignin by actively secreting a set of extracellular enzyme, i.e., lignin-related oxidoreductases, cellulose enzyme and hydrolytic enzyme [2]. In the course of wood decomposition, the degrading fungi secrete substantial amounts of organic acids into their micro-environment to establish optimal conditions for the function of breakdown of crystalline cellulose [3,4]. The bark defends against insects and pathogens, and protects against fire and herbivores [5,6]
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