title: Relationship between NaCl- and H2O2-induced cytosolic Ca2+ increases in response to stress in Arabidopsis.
abstract: Salinity is among the environmental factors that affect plant growth and development and constrain agricultural productivity. Salinity stress triggers increases in cytosolic free Ca(2+) concentration ([Ca(2+)]i) via Ca(2+) influx across the plasma membrane. Salinity stress, as well as other stresses, induces the production of reactive oxygen species (ROS). It is well established that ROS also triggers increases in [Ca(2+)]i. However, the relationship and interaction between salinity stress-induced [Ca(2+)]i increases and ROS-induced [Ca(2+)]i increases remain poorly understood. Using an aequorin-based Ca(2+) imaging assay we have analyzed [Ca(2+)]i changes in response to NaCl and H2O2 treatments in Arabidopsis thaliana. We found that NaCl and H2O2 together induced larger increases in [Ca(2+)]i in Arabidopsis seedlings than either NaCl or H2O2 alone, suggesting an additive effect on [Ca(2+)]i increases. Following a pre-treatment with either NaCl or H2O2, the subsequent elevation of [Ca(2+)]i in response to a second treatment with either NaCl or H2O2 was significantly reduced. Furthermore, the NaCl pre-treatment suppressed the elevation of [Ca(2+)]i seen with a second NaCl treatment more than that seen with a second treatment of H2O2. A similar response was seen when the initial treatment was with H2O2; subsequent addition of H2O2 led to less of an increase in [Ca(2+)]i than did addition of NaCl. These results imply that NaCl-gated Ca(2+) channels and H2O2-gated Ca(2+) channels may differ, and also suggest that NaCl- and H2O2-evoked [Ca(2+)]i may reduce the potency of both NaCl and H2O2 in triggering [Ca(2+)]i increases, highlighting a feedback mechanism. Alternatively, NaCl and H2O2 may activate the same Ca(2+) permeable channel, which is expressed in different types of cells and/or activated via different signaling pathways.
authors.affiliation: The Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu, China ; Center on Plant Environmental Sensing, Institute for Global Change, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, China ; Department of Biology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Zhonghao
authors.initials: Z
authors.lastname: Jiang
authors.forename: Shan
authors.initials: S
authors.lastname: Zhu
authors.forename: Rui
authors.initials: R
authors.lastname: Ye
authors.forename: Yan
authors.initials: Y
authors.lastname: Xue
authors.forename: Amelia
authors.initials: A
authors.lastname: Chen
authors.forename: Lizhe
authors.initials: L
authors.lastname: An
authors.forename: Zhen-Ming
authors.initials: ZM
authors.lastname: Pei
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D002118:Calcium