Genetic Potential for N₂O Metabolism in Tree Tissues: Insights From Nitrogen Cycling Gene Prevalence and nosZ Diversity Across Tree Species

作者：Krishnapriya Thiyagarasaiyar, Dhiraj Paul, Johanna Kerttula, Milja keski-karhu, Kaido Soosaar, Ülo Mander, Sara Hallin, Kateřina Macháčová, Jukka Pumpanen, Henri M.P. Siljanen · 发表于：Microbial Ecology · 年份：2026 · DOI：10.1007/s00248-026-02773-8 · 被引用次数：1 · 研究领域：Plant nutrient uptake and metabolism、Photosynthetic Processes and Mechanisms、Metalloenzymes and iron-sulfur proteins

Nitrous oxide (N2O) is a potent greenhouse gas, and microorganisms play a crucial role in its metabolism. While N2O cycling among soil microorganisms is well studied, there is a major knowledge gap regarding the distribution and diversity of these microorganisms within tree ecosystems. In this study, we aimed to comprehensively assess the potential for nitrogen (N) cycling and the diversity of N2O-reducing microorganisms in shoots (leaves and terminal branches) and wood cores of four tree species — European beech (Fagus sylvatica), European hornbeam (Carpinus betulus), birch (Betula pendula and Betula pubescens) and Norway spruce (Picea abies). We assessed N2O exchange through shoot incubation experiments and measured internal N2O concentrations in stem wood. Inorganic N species were studied as indicators of microbial transformation, and a targeted metagenomic approach was used to determine the relative abundance of N-cycling genes and nosZ clade I and II diversity. Our study revealed that hornbeam shoots showed potential N2O emissions (0.002–0.007 ng N2O g⁻¹ FW h⁻¹), while beech shoots indicated N2O consumption (-0.001 to -0.017 ng N2O g⁻¹ FW h⁻¹). Birch had internal stem wood N2O concentration of + 150.39 ppb, and beech − 9.74 ppb when compared to the ambient concentration. Targeted metagenomic analysis revealed the presence of key nitrification and denitrification genes in both tissue types. In particular, nosZ genes were detected in shoots (0 to 26.48 per 100,000 reads) a...