Fungal ectomycorrhizal community and drought affect root hydraulic properties and soil adherence to roots ofPinus pinaster seedlings |
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Authors: | Marie-Béatrice Bogeat-Triboulot François Bartoli Jean Garbaye Roland Marmeisse Denis Tagu |
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Institution: | (1) UMR INRA-UHP Ecologie et Ecophysiologie Forestières, INRA, 54280 Champenoux, France;(2) Centre de Pédologie Biologique CNRS, BP 5, 54501 Vandoeuvre-lès-Nancy, France;(3) UMR 1136 INRA-UHP Interactions Arbres-Micro-Organismes, INRA, 54280 Champenoux, France;(4) UMR CNRS Ecologie Microbienne du Sol Symbiose Mycorhizienne, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France;(5) Present address: UMR1120, Laboratoire Sols et Environnement, ENSAIA - INPL/INRA, BP 172, 54505 Vandoeuvre les Nancy cedex, France;(6) Present address: UMR BiO3P, INRA Rennes, BP35327, 35653 Le Rheu cedex, France |
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Abstract: | Pinus pinaster seedlings were grown in a sandy dune soil either inoculated withHebeloma cylindrosporum or let to natural colonisation. Six months later, half of the seedlings of both treatments were subjected to a 3-week moderate
drought. Root colonisation analysis showed that root tips were colonised to almost 100% independent of the inoculation. DNA
determination of the ectomycorrhizal morphotypes showed that inoculated seedlings were extensively mycorrhized byH. cylindrosporum (more than 75%) whereas non-inoculated seedlings were mycorrhized by the exotic speciesThelephora terrestris (50%) andLaccaria bicolor (30%) and to a lesser extent byH. cylindrosporum (20%). Drought did not affect these frequencies. Total plant biomass was not affected by the mycorrhizal status or by drought
but the root/shoot biomass ratio as well as the root/leaf surface area ratio were much lower in seedlings extensively colonised
byH. cylindrosporum. Root hydraulic conductivity was higher in plants mainly mycorrhized byH. cylindrosporum, showing that this fungus improved the water uptake capacity of the root system as compared toT. terrestris and/orL. bicolor. This positive effect was also found under drought but to a lesser extent.H. cylindrosporum also increased the amount of root-adhering soil as compared to the other fungal symbionts, illustrating the performance of
this association in aggregating sandy soil particles and developing the rhizosheath. The origin of the reduced root hydraulic
resistance byH. cylindrosporum mycorrhization is discussed for the whole path including soil, soil-root interface and root cortex. |
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Keywords: | ectomycorrhiza Hebeloma cylindrosporum hydraulic conductance root soil aggregation |
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