title: Salinity-induced calcium signaling and root adaptation in Arabidopsis require the calcium regulatory protein annexin1.
abstract: 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.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Anuphon
authors.initials: A
authors.lastname: Laohavisit
authors.forename: Siân L
authors.initials: SL
authors.lastname: Richards
authors.forename: Lana
authors.initials: L
authors.lastname: Shabala
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Renato D D R
authors.initials: RD
authors.lastname: Colaço
authors.forename: Stéphanie M
authors.initials: SM
authors.lastname: Swarbreck
authors.forename: Emma
authors.initials: E
authors.lastname: Shaw
authors.forename: Adeeba
authors.initials: A
authors.lastname: Dark
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Shang
authors.forename: Julia M
authors.initials: JM
authors.lastname: Davies
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D017302:Annexins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020013:Calcium Signaling / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D055049:Salt Tolerance / Q000235:genetics; D012965:Sodium Chloride / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D017302:Annexins; D029681:Arabidopsis Proteins; D012965:Sodium Chloride