The ectomycorrhizal fungus Laccaria bicolor produces lipochitooligosaccharides and uses the common symbiosis pathway to colonize Populus
Kevin R. Cope, Adeline Bascaules, Muthusubramanian Venkateshwaran, Junko Maeda, Kevin Garcia, Cathleen Ma, Jessy Labbé, Sara Jawdy, Edward Steigerwald, Jonathan Setzke, Emmeline Fung, Kimberly Schnell, Yunqian Wang, Nathaniel Schlief, Angad Dhariwal, Steven H. Strauss, Patricia Jargeat, Guillaume Bécard, Virginie Puech-Pagès, and Jean-Michel Ané
15 August 2019, Plant Cell; doi: 10.1105/tpc.18.00676
Mycorrhizal fungi form mutualistic associations with the roots of most land plants and provide them with increased access to limited mineral nutrients in the soil in exchange for carbon derived from photosynthesis. The “common symbiosis pathway” (CSP) is required not only for the arbuscular mycorrhizal symbiosis, but also for the rhizobia–legume and actinorhizal symbioses. Given its role in such diverse symbiotic associations, we hypothesized that the CSP might also play a role in ectomycorrhizal associations. We showed that the ectomycorrhizal fungus Laccaria bicolor produces an array of lipochitooligosaccharides (LCOs) that can trigger both root hair branching in legumes and, most importantly, calcium spiking in the host plant Populus in a CASTOR/POLLUX-dependent manner. Non-sulfated LCOs enhanced lateral root development in Populus in a CCaMK-dependent manner and sulfated LCOs enhanced the colonization of Populus by L. bicolor. The colonization of Populus roots by L. bicolor was reduced in both CASTOR/POLLUX and CCaMK RNA interference lines and the expression of a mycorrhiza-induced phosphate transporter, PT12, was reduced in the CCaMK-RNA interference line compared to wild-type. Altogether, our work demonstrates that L. bicolor uses the CSP for full establishment of its mutualistic association with Populus.
Cope, K. R., A. Bascaules, T. B. Irving, M. Venkateshwaran, J. Maeda, K. Garcia, T. Rush, C. Ma, J. J. Labbe, S. Jawdy, E. Steigerwald, J. Setzke, E. Fung, K. G. Schnell, Y. Wang, N. Schlief, H. Bücking, S. H. Strauss, F. Maillet, P. Jargeat, G. Bécard, V. Puech-Pagès and J.-M. Ane (2019). “The Ectomycorrhizal Fungus Laccaria bicolor Produces Lipochitooligosaccharides and Uses the Common Symbiosis Pathway to Colonize Populus Roots.” The Plant Cell: tpc.00676.02018.