Bacterial effects on arbuscular mycorrhizal fungi and mycorrhiza development as influenced by the bacteria, fungi, and host plant
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Bacterial strains from mycorrhizal roots (three belonging to Comamonadaceae and one to Oxalobacteraceae) and from non-mycorrhizal roots (two belonging to Comamonadaceae) of Medicago truncatula and two reference strains (Collimonas fungivorans Ter331 and Pseudomonas fluorescens C7R12) were tested for their effect on the in vitro saprophytic growth of Glomus mosseae BEG12 and on its colonization of M. truncatula roots. Only the Oxalobacteraceae strain, isolated from barrel medic mycorrhizal roots, and the reference strain P. fluorescens C7R12 promoted both the saprophytic growth and root colonization of G. mosseae BEG12, indicating that they acted as mycorrhiza helper bacteria. Greatest effects were achieved by P. fluorescens C7R12 and its influence on the saprophytic growth of G. mosseae was compared to that on Gigaspora rosea BEG9 to determine if the bacterial stimulation was fungal specific. This fungal specificity, together with plant specificity, was finally evaluated by comparing bacterial effects on arbuscular mycorrhizal symbiosis when each of the fungal species was inoculated to two different plant species (M. truncatula and Lycopersicon esculentum). The results obtained showed that promotion of saprophytic growth by P. fluorescens C7R12 was expressed in vitro towards G. mosseae but not towards G. rosea. Bacterial promotion of mycorhization was also expressed towards G. mosseae, but not G. rosea, in roots of M. truncatula and L. esculentum. Taken together, results indicated that enhancement of arbuscular mycorrhiza development was only induced by a limited number of bacteria, promotion by the most efficient bacterial strain being fungal and not plant specific.
KeywordsArbuscular mycorrhizas Comamonadaceae Oxalobacteraceae Pseudomonas fluorescens C7R12 Mycorrhiza helper bacteria
This study was supported by a doctoral fellowship from Italian MIUR to B. Pivato and by Burgundy regional project 06516CP0155251. The authors are grateful to G. Duc (URLEG-INRA, Dijon, France) for providing seeds of M. truncatula Gaertn. J5, and to W. de Boer (NIOO-KNAW, Centre for Terrestrial Ecology; Heteren, The Netherlands) for providing Collimonas fungivorans Ter331. Authors are grateful to A. Copetta, E. Gamalero, and N. Massa for technical help and stimulating discussions.
- Barea JM, Gryndler M, Lemanceau P, Schüepps H, Azcòn R (2002) The rhizosphere of mycorrhizal plants. In: Gianinazzi S, Schüepps H, Barea JM, Haselwandter K (eds) Mycorrhizal technology in agriculture: from genes to bioproducts. Birkhäuser, Basel, Switzerland, pp 1–18Google Scholar
- Bever JD, Pringle A, Schultz PA (2002) Dynamics within the plant-arbuscular mycorrhizal fungal mutualism: testing the nature of community feedback. In: van der Heijden MGA, Sanders IE (eds) Mycorrhizal Ecology. Springer, Heidelberg, Germany, pp 267–292Google Scholar
- Budi SW, van Tuinen D, Martinotti MG, Gianinazzi S (1999) Isolation from the Sorghum bicolor mycorrhizosphere of a bacterium compatible with arbuscular mycorrhizal development and antagonistic towards soilborne fungal pathogens. Appl Environ Microbiol 11:5148–5150Google Scholar
- de Boer W, Leveau JHJ, Kowalchuk GA, Klein Gunnewiek PJA, Abeln ECA, Figge MJ, Sjollema K, Janse JD, van Veen JA (2004) Collimonas fungivorans gen. nov., sp. nov., a chitinolytic soil bacterium with the ability to grow on living fungal hyphae. Int J Syst Evol Microbiol 54:857–864CrossRefPubMedGoogle Scholar
- Forbes BA, Sahm DE, Weissfeld AS (1998) Bailey & Scott’s diagnostic microbiology, 10th edn. Mosby, St. LouisGoogle Scholar
- Giovannetti M, Sbrana C, Strani P, Agnolucci M, Rinaudo V, Avio L (2003) Genetic diversity of isolates of Glomus mosseae from different geographic areas detected by vegetative compatibility testing and biochemical and molecular analysis. Appl Environ Microbiol 69:616–624CrossRefPubMedPubMedCentralGoogle Scholar
- Kamilova F, Leveau JHJ, Lugtenberg B (2007) Collimonas fungivorans, an unpredicted in vitro but efficient in vivo biocontrol agent for the suppression of tomato foot and root rot. Mycorrhiza 9:1597–1603Google Scholar
- Sanchez L, Weidmann S, Brechenmacher L, Batoux M, van Tuinen D, Lemanceau P, Gianinazzi S, Gianinazzi-Pearson V (2004) Common gene expression in Medicago truncatula roots in response to Pseudomonas fluorescens colonization, mycorrhiza development and nodulation. New Phytol 161:855–863CrossRefGoogle Scholar
- Smith SE, Read DJ (1997) Mycorrhizal Symbiosis. Second Edition. USA. Academic, San Diego, CaliforniaGoogle Scholar
- Trouvelot A, Kough JL, Gianinazzi-Pearson V (1986) Mesure du taux de mycorhization VA d’un système radiculaire. Recherche de méthodes d’estimation ayant une signification fonctionnelle. In: Gianinazzi-Pearson V, Gianinazzi S (eds) Physiological and genetical aspects of mycorrhizae. INRA Presse, Paris, France, pp 217–221Google Scholar