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Abstract
Prokaryotic and eukaryotic microbial symbiotic communities span through kingdoms. The vast microbial gene pool extends the host genome and supports adaptations to changing environmental conditions. Plants are versatile hosts for the symbionts, carrying microbes on the surface, inside tissues, and even within the cells. Insects are equally abundantly colonized by microbial symbionts on the exoskeleton, in the gut, in the hemocoel, and inside the cells. The insect gut is a prolific environment, but it is selective on the microbial species that enter with food. Plants and insects are often highly dependent on each other and frequently interact. Regardless of the accumulating evidence on the microbiomes of both organisms, it remains unclear how much they exchange and modify each other's microbiomes. In this review, we approach this question from the point of view of herbivores that feed on plants, with a special focus on the forest ecosystems. After a brief introduction to the subject, we concentrate on the plant microbiome, the overlap between plant and insect microbial communities, and how the exchange and modification of microbiomes affects the fitness of each host.
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Putkinen A, Siljanen HMP, Laihonen A, Paasisalo I, Porkka K, Tiirola M, Haikarainen I, Tenhovirta S, Pihlatie M. New insight to the role of microbes in the methane exchange in trees: evidence from metagenomic sequencing. THE NEW PHYTOLOGIST 2021; 231:524-536. [PMID: 33780002 DOI: 10.1111/nph.17365] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
Methane (CH4 ) exchange in tree stems and canopies and the processes involved are among the least understood components of the global CH4 cycle. Recent studies have focused on quantifying tree stems as sources of CH4 and understanding abiotic CH4 emissions in plant canopies, with the role of microbial in situ CH4 formation receiving less attention. Moreover, despite initial reports revealing CH4 consumption, studies have not adequately evaluated the potential of microbial CH4 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 CH4 exchange of plants, and particularly in boreal trees. We detected CH4 -producing methanogens and novel monooxygenases, potentially involved in CH4 consumption, in coniferous plants. In addition, our field flux measurements from Norway spruce (Picea abies) canopies demonstrate both net CH4 emissions and uptake, giving further evidence that both production and consumption are relevant to the net CH4 exchange. Our findings, together with the emerging diversity of novel CH4 -producing microbial groups, strongly suggest microbial analyses should be integrated in the studies aiming to reveal the processes and drivers behind plant CH4 exchange.
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Affiliation(s)
- Anuliina Putkinen
- 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
| | - Henri M P Siljanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, 70200, Finland
- Department of Ecogenomics and Archaea Biology, University of Vienna, Vienna, A-1090, Austria
| | - Antti Laihonen
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä, FI-40014, Finland
| | - Inga Paasisalo
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, 70200, Finland
| | - Kaija Porkka
- 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
- Natural Resources Institute Finland, Savonlinna, FI-57200, Finland
| | - Marja Tiirola
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä, FI-40014, Finland
| | - Iikka Haikarainen
- 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
| | - Salla Tenhovirta
- 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
| | - Mari Pihlatie
- 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
- Department of Agricultural Sciences, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, 00014, Finland
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