title: Chloroplast-generated ROS dominate NaCl(-) induced K(+) efflux in wheat leaf mesophyll.
abstract: Mesophyll K(+) retention ability has been recently reported as an important component of salinity stress tolerance in wheat. In order to investigate the role of ROS in regulating NaCl(-)induced K(+) efflux in wheat leaf mesophyll, a series of pharmacological experiments was conducted using MV (methyl viologen, superoxide radical inducer), DPI (an inhibitor of NADPH oxidase), H2O2 (to mimic apoplastic ROS), and EGCG ((-)-Epigallocatechin gallate, ROS scavenger). Mesophyll pre-treatment with 10 μM MV resulted in a significantly higher NaCl(-)induced K(+) efflux in leaf mesophyll, while 50 μM EGCG pre-treatment alleviated K(+) leakage under salt stress. No significant change in NaCl(-)induced K(+) efflux in leaf mesophyll was found in specimens pre-treated by H2O2 and DPI, compared with the control. The highest NaCl(-)induced H(+) efflux in leaf mesophyll was also found in samples pre-treated with MV, suggesting a futile cycle between increased H(+)-ATPase activity and ROS-induced K(+) leak. Overall, it is suggested that, under saline stress, K(+) efflux from wheat mesophyll is mediated predominantly by non-selective cation channels (NSCC) regulated by ROS produced in chloroplasts, at least in bread wheat.
authors.affiliation: a School of Land and Food; University of Tasmania; Hobart , Tas , Australia.
authors.forename: Honghong
authors.initials: H
authors.lastname: Wu
authors.forename: Lana
authors.initials: L
authors.lastname: Shabala
authors.forename: Meixue
authors.initials: M
authors.lastname: Zhou
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
mesh_terms: D002736:Chloroplasts / Q000378:metabolism*; D058503:Mesophyll Cells / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012965:Sodium Chloride; D014908:Triticum / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D011188:Potassium
keywords: K+ channels; K+ retention; ROS; chloroplast; leaf mesophyll