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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.