Ionotropic glutamate receptor (iGluR)-like channels mediate MAMP-induced calcium influx in Arabidopsis thaliana

Mark Kwaaitaal , Rik Huisman , Jens Maintz , Anja Reinstädler , Ralph Panstruga (1)

1 Institute for Biology I, Unit of Plant Molecular Cell Biology

Binding of specific microbial epitopes (microbe-associated molecular patterns, MAMPs) to pattern recognition receptors (PRRs) and subsequent receptor kinase activation are key steps in plant innate immunity. One of the earliest detectable events after MAMP perception is a rapid and transient rise in cytosolic calcium (Ca2+) levels. In plants, knowledge about the signaling events leading to Ca2+ influx and on the molecular identity of the channels involved is scarce. We used a transgenic Arabidopsis thaliana line stably expressing the luminescent aequorin Ca2+ biosensor to monitor pharmacological interference with Ca2+ signatures following treatment with the bacterial peptide MAMPs flg22 and elf18 and the fungal carbohydrate MAMP chitin. Using a comprehensive set of compounds known to impede Ca2+ transport processes in plants and animals we found strong evidence for a prominent role of amino acid-controlled Ca2+ fluxes, probably through ionotropic glutamate receptor (iGluR)-like channels. Interference with amino acid-mediated Ca2+ fluxes modulates MAMP-triggered mitogen-activated protein kinase (MAPK) activity and affects MAMP-induced accumulation of defense gene transcripts. We conclude that the initiation of innate immune responses upon flg22, elf18 and chitin recognition involves apoplastic Ca2+ influx via iGluR-like channels.

Mots clés: Life Sciences

Mark Kwaaitaal, Rik Huisman, Jens Maintz, Anja Reinstädler, Ralph Panstruga. Ionotropic glutamate receptor (iGluR)-like channels mediate MAMP-induced calcium influx in Arabidopsis thaliana. Biochemical Journal, 2011, 440 (3), pp.355-365. ⟨10.1042/BJ20111112⟩. ⟨hal-00658154⟩