Abstract
Hydrogen peroxide is the most stable of the reactive oxygen species (ROS) and is a regulator of development, immunity and adaptation to stress. It frequently acts by elevating cytosolic free Ca2+ ([Ca 2+]cyt) as a second messenger, with activation of plasma membrane Ca2+-permeable influx channels as a fundamental part of this process. At the genetic level, to date only the Ca2 +-permeable Stelar K+ Outward Rectifier (SKOR) channel has been identified as being responsive to hydrogen peroxide. We show here that the ROS-regulated Ca2+ transport protein Annexin 1 in Arabidopsis thaliana (AtANN1) is involved in regulating the root epidermal [Ca 2+]cyt response to stress levels of extracellular hydrogen peroxide. Peroxide-stimulated [Ca2+]cyt elevation (determined using aequorin luminometry) was aberrant in roots and root epidermal protoplasts of the Atann1 knockout mutant. Similarly, peroxide-stimulated net Ca2+ influx and K+ efflux were aberrant in Atann1 root mature epidermis, determined using extracellular vibrating ion-selective microelectrodes. Peroxide induction of GSTU1 (Glutathione-S-Transferase1 Tau 1), which is known to be [Ca2+]cyt-dependent was impaired in mutant roots, consistent with a lesion in signalling. Expression of AtANN1 in roots was suppressed by peroxide, consistent with the need to restrict further Ca2+ influx. Differential regulation of annexin expression was evident, with AtANN2 down-regulation but up-regulation of AtANN3 and AtANN4. Overall the results point to involvement of AtANN1 in shaping the root peroxide-induced [Ca2+]cyt signature and downstream signalling.
Original language | English |
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Pages (from-to) | 136-145 |
Number of pages | 10 |
Journal | Plant Journal |
Volume | 77 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jan 2014 |
Externally published | Yes |