title: Aquaporin functionality in relation to H+-ATPase activity in root cells of Capsicum annuum grown under salinity.
abstract: As water and nutrient uptake should be related in the response of plants to salinity, the aim of this paper is to establish whether or not aquaporin functionality is related to H+-ATPase activity in root cells of pepper (Capsicum annuum L.) plants. Thus, H+-ATPase activity was measured in plasma membrane vesicles isolated from roots and aquaporin functionality was measured using a cell pressure probe in intact roots. Salinity was applied as 60 mM NaCl or 60 mM KCl, to determine which ion (Na+, K+ or Cl-) is producing the effects. We also investigated whether the effects of both salts were ameliorated by Ca2+. Similar results were obtained for cell hydraulic conductivity, Lpc, and H+-ATPase activity, large reductions in the presence at NaCl or KCl and an ameliorative effect of Ca2+. However, fusicoccin (an activator of H+-ATPase) did not alter osmotic water permeability of protoplasts isolated from roots. Addition of Hg2+ inhibited both ATPase and aquaporins, but ATPase also contains Hg-binding sites. Therefore, the results indicate that H+-ATPase and aquaporin activities may not be related in pepper plants.
authors.affiliation: Departamento de Nutrición y Fisiología Vegetal, Centro de Edafología y Biología Aplicada del Segura, CSIC, PO Box 4195, 30080 Murcia, Spain.
authors.forename: M. Carmen
authors.initials: MC
authors.lastname: Martínez-Ballesta
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez
authors.forename: Micaela
authors.initials: M
authors.lastname: Carvajal