title: Mechanisms of salt tolerance in habanero pepper plants (Capsicum chinense Jacq.): Proline accumulation, ions dynamics and sodium root-shoot partition and compartmentation.
abstract: Despite its economic relevance, little is known about salt tolerance mechanisms in pepper plants. To address this question, we compared differences in responses to NaCl in two Capsicum chinense varieties: Rex (tolerant) and Chichen-Itza (sensitive). Under salt stress (150 mM NaCl over 7 days) roots of Rex variety accumulated 50 times more compatible solutes such as proline compared to Chichen-Itza. Mineral analysis indicated that Na(+) is restricted to roots by preventing its transport to leaves. Fluorescence analysis suggested an efficient Na(+) compartmentalization in vacuole-like structures and in small intracellular compartments in roots of Rex variety. At the same time, Na(+) in Chichen-Itza plants was compartmentalized in the apoplast, suggesting substantial Na(+) extrusion. Rex variety was found to retain more K(+) in its roots under salt stress according to a mineral analysis and microelectrode ion flux estimation (MIFE). Vanadate-sensitive H(+) efflux was higher in Chichen-Itza variety plants, suggesting a higher activity of the plasma membrane H(+)-ATPase, which fuels the extrusion of Na(+), and, possibly, also the re-uptake of K(+). Our results suggest a combination of stress tolerance mechanisms, in order to alleviate the salt-induced injury. Furthermore, Na(+) extrusion to apoplast does not appear to be an efficient strategy for salt tolerance in pepper plants.
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Bojórquez-Quintal
authors.affiliation: Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México.
authors.forename: Ana
authors.initials: A
authors.lastname: Velarde-Buendía
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Angela
authors.initials: A
authors.lastname: Ku-González
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Mildred
authors.initials: M
authors.lastname: Carillo-Pech
authors.affiliation: Unidad de Ciencias del Agua, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ortega-Camacho
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Ileana
authors.initials: I
authors.lastname: Echevarría-Machado
authors.affiliation: Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México.
authors.forename: Igor
authors.initials: I
authors.lastname: Pottosin
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.
authors.forename: Manuel
authors.initials: M
authors.lastname: Martínez-Estévez
keywords: H+-ATPase; ion fluxes; pepper; potassium retention; proline accumulation; roots; salt tolerance; sodium compartmentalization