title: Regulation of hormonal responses of sweet pepper as affected by salinity and elevated CO2 concentration.
abstract: This study examines the extent to which the predicted CO2 -protective effects on the inhibition of growth, impairment of photosynthesis and nutrient imbalance caused by saline stress are mediated by an effective adaptation of the endogenous plant hormonal balance. Therefore, sweet pepper plants (Capsicum annuum, cv. Ciclón) were grown at ambient or elevated [CO2] (400 or 800 µmol mol(-1)) with a nutrient solution containing 0 or 80 mM NaCl. The results show that, under saline conditions, elevated [CO2] increased plant dry weight, leaf area, leaf relative water content and net photosynthesis compared with ambient [CO2], whilst the maximum potential quantum efficiency of photosystem II was not modified. In salt-stressed plants, elevated [CO2 ] increased leaf NO3(-) concentration and reduced Cl(-) concentration. Salinity stress induced ABA accumulation in the leaves but it was reduced in the roots at high [CO2], being correlated with the stomatal response. Under non-stressed conditions, IAA was dramatically reduced in the roots when high [CO2] was applied, which resulted in greater root DW and root respiration. Additionally, the observed high CK concentration in the roots (especially tZR) could prevent downregulation of photosynthesis at high [CO2], as the N level in the leaves was increased compared with the ambient [CO2], under salt-stress conditions. These results demonstrate that the hormonal balance was altered by the [CO2], which resulted in significant changes at the growth, gas exchange and nutritional levels.
authors.affiliation: Equipo de Calidad Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), 30150, Murcia, Spain.
authors.forename: María Carmen
authors.initials: MC
authors.lastname: Piñero
authors.forename: Fabrice
authors.initials: F
authors.lastname: Houdusse
authors.forename: Jose M
authors.initials: JM
authors.lastname: Garcia-Mina
authors.forename: María
authors.initials: M
authors.lastname: Garnica
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Del Amor
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D002212:Capsicum / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D002245:Carbon Dioxide / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects; D054712:Salinity
chemical_list: D002712:Chlorides; D003583:Cytokinins; D007210:Indoleacetic Acids; D009566:Nitrates; D045332:Photosystem II Protein Complex; D010937:Plant Growth Regulators; D002734:Chlorophyll; D002245:Carbon Dioxide; D000040:Abscisic Acid