title: New evidence about the relationship between water channel activity and calcium in salinity-stressed pepper plants.
abstract: This study, of how Ca2+ availability (intracellular, extracellular or linked to the membrane) influences the functionality of aquaporins of pepper (Capsicum annuum L.) plants grown under salinity stress, was carried out in plants treated with NaCl (50 mM), CaCl2 (10 mM), and CaCl2 (10 mM) + NaCl (50 mM). For this, water transport through the plasma membrane of isolated protoplasts, and the involvement of aquaporins and calcium (extracellular, intracellular and linked to the membrane) has been determined. After these treatments, it could be seen that the calcium concentration was reduced in the apoplast, in the cells and on the plasma membrane of roots of pepper plants grown under saline conditions; these concentrations were increased or restored when extra calcium was added to the nutrient solution. Protoplasts extracted from plants grown under Ca2+ starvation showed no aquaporin functionality. However, for the protoplasts to which calcium was added, an increase of aquaporin functionality of the plasma membrane was observed [osmotic water permeability (Pf) inhibition after Hg addition]. Interestingly, when verapamil (a Ca2+ channel blocker) was added, no functionality was observed, even when Ca2+ was added with verapamil. Therefore, calcium seems to be involved in plasma membrane aquaporin regulation via a chain of processes within the cell but not by alteration of the stability of the plasma membrane.
authors.affiliation: Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura-CSIC, Apdo. Correos 164, 30100 Espinardo, Murcia, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Cabañero
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Martínez-Ballesta
authors.forename: José A
authors.initials: JA
authors.lastname: Teruel
authors.forename: Micaela
authors.initials: M
authors.lastname: Carvajal
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000502:physiology; D020346:Aquaporins / Q000502:physiology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology*; D002212:Capsicum / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D009995:Osmosis; D018517:Plant Roots / Q000737:chemistry / Q000166:cytology; D012965:Sodium Chloride / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020346:Aquaporins; D002121:Calcium Channel Blockers; D012965:Sodium Chloride; D014700:Verapamil; D000251:Adenosine Triphosphatases; D002122:Calcium Chloride; D002118:Calcium