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SUMMARY Extracellular ATP (eATP) is known to act as a danger signal in both plants and animals. In plants, eATP is recognized by the plasma membrane (PM)‐localized receptor P2K1 (LecRK‐I.9). Among the first measurable responses to eATP addition is a rapid rise in cytoplasmic free calcium levels ([Ca2+]cyt), which requires P2K1. However, the specific transporter/channel proteins that mediate this rise in [Ca2+]cytare unknown. Through a forward genetic screen, we identified an Arabidopsis ethylmethanesulfonate (EMS) mutant impaired in the [Ca2+]cytresponse to eATP. Positional cloning revealed that the mutation resided in thecngc6gene, which encodes cyclic nucleotide‐gated ion channel 6 (CNGC6). Mutation of theCNGC6gene led to a notable decrease in the PM inward Ca2+current in response to eATP. eATP‐induced mitogen‐activated protein kinase activation and gene expression were also significantly lower incngc6mutant plants. In addition,cngc6mutant plants were also more susceptible to the bacterial pathogenPseudomonas syringae. Taken together, our results indicate that CNGC6 plays a crucial role in mediating eATP‐induced [Ca2+]cytsignaling, as well as plant immunity.
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Arabidopsis thaliana CYCLIC NUCLEOTIDE‐GATED CHANNEL2 mediates extracellular ATP signal transduction in root epidermis
Summary Damage can be signalled by extracellular ATP (eATP) using plasma membrane (PM) receptors to effect cytosolic free calcium ion ([Ca2+]cyt) increase as a second messenger. The downstream PM Ca2+channels remain enigmatic. Here, theArabidopsis thalianaCa2+channel subunit CYCLIC NUCLEOTIDE‐GATED CHANNEL2 (CNGC2) was identified as a critical component linking eATP receptors to downstream [Ca2+]cytsignalling in roots.Extracellular ATP‐induced changes in single epidermal cell PM voltage and conductance were measured electrophysiologically, changes in root [Ca2+]cytwere measured with aequorin, and root transcriptional changes were determined by quantitative real‐time PCR. Twocngc2loss‐of‐function mutants were used:cngc2‐3anddefence not death1(which expresses cytosolic aequorin).Extracellular ATP‐induced transient depolarization of Arabidopsis root elongation zone epidermal PM voltage was Ca2+dependent, requiring CNGC2 but not CNGC4 (its channel co‐subunit in immunity signalling). Activation of PM Ca2+influx currents also required CNGC2. The eATP‐induced [Ca2+]cytincrease and transcriptional response incngc2roots were significantly impaired.CYCLIC NUCLEOTIDE‐GATED CHANNEL2 is required for eATP‐induced epidermal Ca2+influx, causing depolarization leading to [Ca2+]cytincrease and damage‐related transcriptional response.
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- Award ID(s):
- 1826803
- PAR ID:
- 10364450
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 234
- Issue:
- 2
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 412-421
- Size(s):
- p. 412-421
- Sponsoring Org:
- National Science Foundation
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