Cyclic Nucleotide-Gated Ion Channel 6 Mediates Thermotolerance in Seedlings by Regulating Hydrogen Peroxide Production Cytosolic Calcium Ions.

We previously reported the involvement of cyclic nucleotide-gated ion channel 6 (CNGC6) and hydrogen peroxide (HO) in plant responses to heat shock (HS). To demonstrate their relationship with plant thermotolerance, we assessed the effect of HS on several groups of () seedlings: wild-type, mutant, and its complementation line. Under exposure to HS, the level of HO was lower in the mutant seedlings than in the wild-type (WT) seedlings but obviously increased in the complementation line. The treatment of seeds with calcium ions (Ca) increased the HO levels in the seedlings under HS treatment, whereas treatment with a Ca chelator (EGTA) inhibited it, indicating that CNGC6 may stimulate the accumulation of HO in a manner dependent on an increase in cytosolic Ca ([Ca]). This point was verified by phenotypic observations and thermotolerance testing with transgenic plants overexpressing and (two genes involved in HS-responsive HO production), respectively, in a background. Real-time reverse transcription-polymerase chain reactions and Western blotting suggested that CNGC6 enhanced the gene transcription of HS factors (HSFs) and the accumulation of HS proteins (HSPs) HO. These upon results indicate that HO acts downstream of CNGC6 in the HS signaling pathway, increasing our understanding of the initiation of plants responses to high temperatures.