These authors contributed equally to this work.
Short-chain chitin oligomers from arbuscular mycorrhizal fungi trigger nuclear Ca2+ spiking in Medicago truncatula roots and their production is enhanced by strigolactone
Article first published online: 6 FEB 2013
© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust
Volume 198, Issue 1, pages 190–202, April 2013
How to Cite
Genre, A., Chabaud, M., Balzergue, C., Puech-Pagès, V., Novero, M., Rey, T., Fournier, J., Rochange, S., Bécard, G., Bonfante, P. and Barker, D. G. (2013), Short-chain chitin oligomers from arbuscular mycorrhizal fungi trigger nuclear Ca2+ spiking in Medicago truncatula roots and their production is enhanced by strigolactone. New Phytologist, 198: 190–202. doi: 10.1111/nph.12146
- Issue published online: 25 FEB 2013
- Article first published online: 6 FEB 2013
- Manuscript Accepted: 5 DEC 2012
- Manuscript Received: 15 OCT 2012
- Converging Technologies project funded by Regione Piemonte
- Italian National project PRIN 2008
- French National Research Agency. Grant Number: ANR-08-BLAN-0029-01
- French National Centre Scientific Research. Grant Number: PICS 4267
- French Ministry of Research and Higher Education
- arbuscular mycorrhiza (AM);
- chitin oligomers;
- common SYM pathway;
- fungal–plant signalling;
- germinated spore exudates;
- Medicago truncatula ;
- nuclear calcium spiking;
- The primary objective of this study was to identify the molecular signals present in arbuscular mycorrhizal (AM) germinated spore exudates (GSEs) responsible for activating nuclear Ca2+ spiking in the Medicago truncatula root epidermis.
- Medicago truncatula root organ cultures (ROCs) expressing a nuclear-localized cameleon reporter were used as a bioassay to detect AM-associated Ca2+ spiking responses and LC-MS to characterize targeted molecules in GSEs.
- This approach has revealed that short-chain chitin oligomers (COs) can mimic AM GSE-elicited Ca2+ spiking, with maximum activity observed for CO4 and CO5. This spiking response is dependent on genes of the common SYM signalling pathway (DMI1/DMI2) but not on NFP, the putative Sinorhizobium meliloti Nod factor receptor. A major increase in the CO4/5 concentration in fungal exudates is observed when Rhizophagus irregularis spores are germinated in the presence of the synthetic strigolactone analogue GR24. By comparison with COs, both sulphated and nonsulphated Myc lipochito-oligosaccharides (LCOs) are less efficient elicitors of Ca2+ spiking in M. truncatula ROCs.
- We propose that short-chain COs secreted by AM fungi are part of a molecular exchange with the host plant and that their perception in the epidermis leads to the activation of a SYM-dependent signalling pathway involved in the initial stages of fungal root colonization.