title: Short-chain chitin oligomers from arbuscular mycorrhizal fungi trigger nuclear Ca2+ spiking in Medicago truncatula roots and their production is enhanced by strigolactone.
abstract: 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 Ca(2+) 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 Ca(2+) 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 Ca(2+) 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 Ca(2+) 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.
authors: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
authors: Andrea
authors: A
authors: Genre
authors: Laboratory of Plant-Microbe Interactions, Institut National de la Recherche Agronomique (UMR 441), Centre National de la Recherche Scientifique (UMR 2594), CS 52627, 31326, Castanet-Tolosan, France.
authors: Mireille
authors: M
authors: Chabaud
authors: Laboratoire de Recherche en Sciences Végétales, UPS, Université de Toulouse, UMR5546, BP42617, F-31326, Castanet-Tolosan Cedex, France.|CNRS, UMR5546, BP 42617, F-31326, Castanet-Tolosan Cedex, France.
authors: Coline
authors: C
authors: Balzergue
authors: Laboratoire de Recherche en Sciences Végétales, UPS, Université de Toulouse, UMR5546, BP42617, F-31326, Castanet-Tolosan Cedex, France.|CNRS, UMR5546, BP 42617, F-31326, Castanet-Tolosan Cedex, France.
authors: Virginie
authors: V
authors: Puech-Pagès
authors: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
authors: Mara
authors: M
authors: Novero
authors: Laboratoire de Recherche en Sciences Végétales, UPS, Université de Toulouse, UMR5546, BP42617, F-31326, Castanet-Tolosan Cedex, France.|CNRS, UMR5546, BP 42617, F-31326, Castanet-Tolosan Cedex, France.
authors: Thomas
authors: T
authors: Rey
authors: Laboratory of Plant-Microbe Interactions, Institut National de la Recherche Agronomique (UMR 441), Centre National de la Recherche Scientifique (UMR 2594), CS 52627, 31326, Castanet-Tolosan, France.
authors: Joëlle
authors: J
authors: Fournier
authors: Laboratoire de Recherche en Sciences Végétales, UPS, Université de Toulouse, UMR5546, BP42617, F-31326, Castanet-Tolosan Cedex, France.|CNRS, UMR5546, BP 42617, F-31326, Castanet-Tolosan Cedex, France.
authors: Soizic
authors: S
authors: Rochange
authors: Laboratoire de Recherche en Sciences Végétales, UPS, Université de Toulouse, UMR5546, BP42617, F-31326, Castanet-Tolosan Cedex, France.|CNRS, UMR5546, BP 42617, F-31326, Castanet-Tolosan Cedex, France.
authors: Guillaume
authors: G
authors: Bécard
authors: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
authors: Paola
authors: P
authors: Bonfante
authors: Laboratory of Plant-Microbe Interactions, Institut National de la Recherche Agronomique (UMR 441), Centre National de la Recherche Scientifique (UMR 2594), CS 52627, 31326, Castanet-Tolosan, France.
authors: David G
authors: DG
authors: Barker
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D002686:Chitin / Q000494:pharmacology*; D054884:Host-Pathogen Interactions / Q000187:drug effects; D007783:Lactones / Q000494:pharmacology*; D046913:Medicago truncatula / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology*; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000187:drug effects / Q000378:metabolism*; D009844:Oligosaccharides / Q000494:pharmacology; D019441:Plant Epidermis / Q000187:drug effects / Q000382:microbiology; D018517:Plant Roots / Q000187:drug effects / Q000382:microbiology*; D013172:Spores, Fungal / Q000187:drug effects / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C507382:GR24 compound; D007783:Lactones; D009844:Oligosaccharides; D002686:Chitin; C012238:chitotetrose
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