JXB Advance Access originally published online on March 8, 2007
Journal of Experimental Botany 2007 58(6):1473-1483; doi:10.1093/jxb/erm009
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RESEARCH PAPER |
Common mycorrhizal networks provide a potential pathway for the transfer of hydraulically lifted water between plants
1Centre for Conservation Biology, The University of California, Riverside, CA 92521, USA
2Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
3Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60201, USA
4Departamento de Conservación de Suelos y Aguas, Centro de Edafología y Biología Aplicada del Segura-CSIC, Campus de Espinardo, PO Box 4195, E-30100 Murcia, Spain
To whom correspondence should be addressed. E-mail: l-egerton{at}northwestern.edu
Plant roots may be linked by shared or common mycorrhizal networks (CMNs) that constitute pathways for the transfer of resources among plants. The potential for water transfer by such networks was examined by manipulating CMNs independently of plant roots in order to isolate the role(s) of ectomycorrhizal (EM) and arbuscular mycorrhizal fungal (AMF) networks in the plant water balance during drought (soil water potential –5.9 MPa). Fluorescent tracer dyes and deuterium-enriched water were used to follow the pathways of water transfer from coastal live oak seedlings (Quercus agrifolia Nee; colonized by EM and AMF) conducting hydraulic lift (HL) into the roots of water-stressed seedlings connected only by EM (Q. agrifolia) or AMF networks (Q. agrifolia, Eriogonum fasciculatum Benth., Salvia mellifera Greene, Keckiella antirrhinoides Benth). When connected to donor plants by hyphal linkages, deuterium was detected in the transpiration flux of receiver oak plants, and dye-labelled extraradical hyphae, rhizomorphs, mantles, and Hartig nets were observed in receiver EM oak roots, and in AMF hyphae of Salvia. Hyphal labelling was scarce in Eriogonum and Keckiella since these species are less dependent on AMF. The observed patterns of dye distribution also indicated that only a small percentage of mycorrhizal roots and extraradical hyphae were involved with water transfer among plants. Our results suggest that the movement of water by CMNs is potentially important to plant survival during drought, and that the functional ecophysiological traits of individual mycorrhizal fungi may be a component of this mechanism.
Key words: Common mycorrhizal networks, deuterium, drought, fluorescent tracers, hydraulic lift, rhizomorph, Quercus agrifolia
* The first two authors contributed equally to this work.
Received 14 December 2006; Revised 3 January 2007 Accepted 8 January 2007
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