Salinity (NaCl) stress impairs plant growth and inflicts severe crop losses. In roots, increasing extracellular NaCl causes Ca²⁺ influx to elevate cytosolic free Ca²⁺ ([Ca²⁺]_cyt) as a second messenger for adaptive signaling. Amplification of the signal involves plasma membrane reduced nicotinamide adenine dinucleotide phosphate oxidase activation, with the resultant reactive oxygen species triggering Ca²⁺ influx. The genetic identities of the Ca²⁺-permeable channels involved in generating the [Ca²⁺]cyt signal are unknown. Potential candidates in the model plant Arabidopsis (Arabidopsis thaliana) include annexin1 (AtANN1). Here, luminescent detection of [Ca²⁺]_cyt showed that AtANN1 responds to high extracellular NaCl by mediating reactive oxygen species-activated Ca²⁺ influx across the plasma membrane of root epidermal protoplasts. Electrophysiological analysis revealed that root epidermal plasma membrane Ca²⁺ influx currents activated by NaCl are absent from the Atann1 loss-of-function mutant. Both adaptive signaling and salt-responsive production of secondary roots are impaired in the loss-of-function mutant, thus identifying AtANN1 as a key component of root cell adaptation to salinity.

Item Type:	Refereed Article
Keywords:	root adaptation, Arabidopsis, calcium, annexin1
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Grains and seeds
Objective Field:	Grains and seeds not elsewhere classified
UTAS Author:	Shabala, L (Associate Professor Lana Shabala)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	86961
Year Published:	2013
Web of Science® Times Cited:	96
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2013-11-04
Last Modified:	2014-05-28
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