title: Anion Channel Inhibitor NPPB-Inhibited Fluoride Accumulation in Tea Plant (Camellia sinensis) Is Related to the Regulation of Ca²⁺, CaM and Depolarization of Plasma Membrane Potential.
abstract: Tea plant is known to be a hyper-accumulator of fluoride (F). Over-intake of F has been shown to have adverse effects on human health, e.g., dental fluorosis. Thus, understanding the mechanisms fluoride accumulation and developing potential approaches to decrease F uptake in tea plants might be beneficial for human health. In the present study, we found that pretreatment with the anion channel inhibitor NPPB reduced F accumulation in tea plants. Simultaneously, we observed that NPPB triggered Ca(2+) efflux from mature zone of tea root and significantly increased relative CaM in tea roots. Besides, pretreatment with the Ca(2+) chelator (EGTA) and CaM antagonists (CPZ and TFP) suppressed NPPB-elevated cytosolic Ca(2+) fluorescence intensity and CaM concentration in tea roots, respectively. Interestingly, NPPB-inhibited F accumulation was found to be significantly alleviated in tea plants pretreated with either Ca(2+) chelator (EGTA) or CaM antagonists (CPZ and TFP). In addition, NPPB significantly depolarized membrane potential transiently and we argue that the net Ca(2+) and H⁺ efflux across the plasma membrane contributed to the restoration of membrane potential. Overall, our results suggest that regulation of Ca(2+)-CaM and plasma membrane potential depolarization are involved in NPPB-inhibited F accumulation in tea plants.
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China. zhangxianchen360@163.com.
authors.forename: Xian-Chen
authors.initials: XC
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China. hjgao@ahau.edu.cn.|School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China. hjgao@ahau.edu.cn.
authors.forename: Hong-Jian
authors.initials: HJ
authors.lastname: Gao
authors.affiliation: College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095 China. yangtianyuan2008@163.com.
authors.forename: Tian-Yuan
authors.initials: TY
authors.lastname: Yang
authors.affiliation: School of Land and Food, University of Tasmania, Hobart, Tasmania 7001, Australia. Honghong.Wu@utas.edu.au.
authors.forename: Hong-Hong
authors.initials: HH
authors.lastname: Wu
authors.affiliation: School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China. ymwang1008@163.com.
authors.forename: Yu-Mei
authors.initials: YM
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China. zzz@ahau.edu.cn.
authors.forename: Zheng-Zhu
authors.initials: ZZ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China. wanxiaochun360@163.com.
authors.forename: Xiao-Chun
authors.initials: XC
authors.lastname: Wan
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D028241:Camellia sinensis / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005459:Fluorides / Q000378:metabolism*; D016623:Ion Pumps / Q000037:antagonists & inhibitors*; D008564:Membrane Potentials / Q000187:drug effects; D009579:Nitrobenzoates / Q000494:pharmacology*; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D002147:Calmodulin; D016623:Ion Pumps; D009579:Nitrobenzoates; D010940:Plant Proteins; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D005459:Fluorides; D002118:Calcium
keywords: Ca2+ efflux; Ca2+ fluorescence; CaM; NPPB; fluoride; tea plant