Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki, 00014, Finland.
Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, Helsinki, 00560, Finland.
New Phytol. 2021 Jul;231(2):524-536. doi: 10.1111/nph.17365. Epub 2021 May 2.
Methane (CH ) exchange in tree stems and canopies and the processes involved are among the least understood components of the global CH cycle. Recent studies have focused on quantifying tree stems as sources of CH and understanding abiotic CH emissions in plant canopies, with the role of microbial in situ CH formation receiving less attention. Moreover, despite initial reports revealing CH consumption, studies have not adequately evaluated the potential of microbial CH oxidation within trees. In this paper, we discuss the current level of understanding on these processes. Further, we demonstrate the potential of novel metagenomic tools in revealing the involvement of microbes in the CH exchange of plants, and particularly in boreal trees. We detected CH -producing methanogens and novel monooxygenases, potentially involved in CH consumption, in coniferous plants. In addition, our field flux measurements from Norway spruce (Picea abies) canopies demonstrate both net CH emissions and uptake, giving further evidence that both production and consumption are relevant to the net CH exchange. Our findings, together with the emerging diversity of novel CH -producing microbial groups, strongly suggest microbial analyses should be integrated in the studies aiming to reveal the processes and drivers behind plant CH exchange.
树干和树冠中的甲烷 (CH ) 交换及其相关过程是全球 CH 循环中了解最少的部分之一。最近的研究集中于量化树干作为 CH 的源，并理解植物冠层中的非生物 CH 排放，而微生物原位 CH 形成的作用则受到较少关注。此外，尽管最初的报告揭示了 CH 的消耗，但研究并未充分评估树木内微生物 CH 氧化的潜力。本文讨论了目前对这些过程的理解程度。此外，我们展示了新型宏基因组工具在揭示微生物参与植物 CH 交换中的潜力，特别是在北方树木中。我们在针叶植物中检测到了产生 CH 的产甲烷菌和可能参与 CH 消耗的新型单加氧酶。此外，我们在挪威云杉 (Picea abies) 树冠上进行的田间通量测量表明，存在净 CH 排放和吸收，进一步证明了生产和消耗都与净 CH 交换有关。我们的研究结果以及新兴的新型 CH 产生微生物群的多样性强烈表明，在旨在揭示植物 CH 交换背后的过程和驱动因素的研究中，应整合微生物分析。
