Record ID No. |
80 |
Author(s) |
Reddy, SM., Hitchin, S., Melayah, D., Pandey, A.K., Raffier, C., Henderson, J., Marmeisse, R., Gay, G , 2006 |
Affiliation |
Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR 5505), USC INRA Ecologie Microbienne, 1193, Bat A Lwoff, 43 Blvd 11 Nove, F-69622 Villeurbanne, France |
Title |
The auxin-inducible GH3 homologue Pp-GH3.16 is downregulated in Pinus pinaster root systems on ectomycorrhizal symbiosis establishment |
Source. Vol.(no):Page |
New phytologist. 170(2):391-400p. |
Categories |
Ectomycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Hormones |
Host |
Pinus pinaster |
Organism |
Hebeloma cylindrosporum, Rhizopogon roseolus |
Country |
France, Europe |
Abstracts |
In an attempt to determine whether auxin-regulated plant genes play a role in ectomycorrhizal symbiosis establishment, we screened a Pinus pinaster root cDNA library for auxin-upregulated genes. This allowed the identification of a cDNA, Pp-GH3.16, which encodes a polypeptide sharing extensive homologies with GH3 proteins of different plants. Pp-GH3.16 was specifically upregulated by auxins and was not affected by cytokinin, gibberellin, abscisic acid or ethylene, or by heat shock, water stress or anoxia. Pp-GH3.16 mRNAs were quantified in pine roots inoculated with two ectomycorrhizal fungi, Hebeloma cylindrosporum and Rhizopogon roseolus. Surprisingly, Pp-GH3.16 was downregulated following inoculation with both fungal species. The downregulation was most rapid on establishment of symbiosis with an indole-3-acetic acid (IAA)-overproducing mutant of H. cylindrosporum, which overproduced mycorrhizas characterized by a hypertrophic Hartig net. This indicates that, despite being auxin-inducible, Pp-GH3.16 can be downregulated on establishment of symbiosis with a fungus that releases auxin. By contrast, Pp-GH3.16 was not downregulated in pine root systems inoculated with a nonmycorrhizal mutant of H. cylindrosporum, suggesting that the downregulation we observed in mycorrhizal root systems was a component of the molecular cross-talk between symbiotic partners at the origin of differentiation of symbiotic structures. |