Routes to roots: direct evidence of water transport by arbuscular mycorrhizal fungi to host plants

Journal Article · 30 June 2022 · New Phytologist

DOI: https://doi.org/10.1111/nph.18281 · OSTI ID:1874597

Kakouridis, Anne  ^[1]; Hagen, John A.  ^[2]; Kan, Megan P.  ^[3]; Mambelli, Stefania  ^[4]; Feldman, Lewis J. ^[2]; Herman, Donald J. ^[1]; Weber, Peter K.  ^[5]; Pett‐Ridge, Jennifer  ^[6]; Firestone, Mary K.  ^[2]

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1. University of California Berkeley Berkeley CA 94720 USA, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
2. University of California Berkeley Berkeley CA 94720 USA
3. University of California Berkeley Berkeley CA 94720 USA, Lawrence Livermore National Laboratory Livermore CA 94550 USA
4. University of California Berkeley Berkeley CA 94720 USA, Center for Stable Isotope Biogeochemistry Berkeley CA 94720 USA
5. Lawrence Livermore National Laboratory Livermore CA 94550 USA
6. Lawrence Livermore National Laboratory Livermore CA 94550 USA, University of California Merced Merced CA 95344 USA

Summary Arbuscular mycorrhizal fungi (AMF) can help mitigate plant responses to water stress, but it is unclear whether AMF do so by indirect mechanisms, direct water transport to roots, or a combination of the two. Here, we investigated if and how the AMF Rhizophagus intraradices transported water to the host plant Avena barbata , wild oat. We used two‐compartment microcosms, isotopically labeled water, and a fluorescent dye to directly track and quantify water transport by AMF across an air gap to host plants. Plants grown with AMF that had access to a physically separated compartment containing ¹⁸ O‐labeled water transpired almost twice as much as plants with AMF excluded from that compartment. Using an isotopic mixing model, we estimated that water transported by AMF across the air gap accounted for 34.6% of the water transpired by host plants. In addition, a fluorescent dye indicated that hyphae were able to transport some water via an extracytoplasmic pathway. Our study provides direct evidence that AMF can act as extensions of the root system along the soil–plant–air continuum of water movement, with plant transpiration driving water flow along hyphae outside of the hyphal cell membrane.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC02-05CH11231; AC52-07NA27344; SC0010570; SC0016247; SC0020163
• OSTI ID: 1874597
• Journal Information: New Phytologist, Journal Name: New Phytologist Journal Issue: 1 Vol. 236; ISSN 0028-646X
• Publisher: Wiley-BlackwellCopyright Statement
• Country of Publication: United Kingdom
• Language: English