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Phytomelatonin receptor PMTR 1‐mediated signaling regulates stomatal closure in Arabidopsis thaliana

2018; Wiley; Volume: 65; Issue: 2 Linguagem: Inglês

10.1111/jpi.12500

1600-079X

Jian Wei, Dongxu Li, Jiarong Zhang, Shan Chi, Zed Rengel, Zhongbang Song, Qi Chen,

Plant Molecular Biology Research

Melatonin has been detected in plants in 1995; however, the function and signaling pathway of this putative phytohormone are largely undetermined due to a lack of knowledge about its receptor. Here, we discovered the first phytomelatonin receptor (CAND2/PMTR1) in Arabidopsis thaliana and found that melatonin governs the receptor-dependent stomatal closure. The application of melatonin induced stomatal closure through the heterotrimeric G protein α subunit-regulated H2 O2 and Ca2+ signals. The Arabidopsis mutant lines lacking AtCand2 that encodes a candidate G protein-coupled receptor were insensitive to melatonin-induced stomatal closure. Accordingly, the melatonin-induced H2 O2 production and Ca2+ influx were completely abolished in cand2. CAND2 is a membrane protein that interacts with GPA1 and the expression of AtCand2 was tightly regulated by melatonin in various organs and guard cells. CAND2 showed saturable and specific 125 I-melatonin binding, with apparent Kd (dissociation constant) of 0.73 ± 0.10 nmol/L (r2 = .99), demonstrating this protein is a phytomelatonin receptor (PMTR1). Our results suggest that the phytomelatonin regulation of stomatal closure is dependent on its receptor CAND2/PMTR1-mediated H2 O2 and Ca2+ signaling transduction cascade.