Relationship between NaCl- and H2O2-induced cytosolic Ca2+ increases in response to stress in Arabidopsis.
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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.
SUBMITTER: Jiang Z
PROVIDER: S-EPMC3790670 | biostudies-literature | 2013
REPOSITORIES: biostudies-literature
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