The aim of the study was to investigate the influence of drought stress on the responses of two Mediterranean tree species, characterized by different drought-sensitivity, to a single pulse of ozone (O3). The behaviour of Quercus cerris(drought-sensitive) and Q. pubescens(mild-drought-sensitive) was evaluated in terms of ecophysiology and cross-talk responses among signalling molecules. Control plants maintained in well-watered and under filtered air conditions were compared with individuals subjected to drought (20% of the effective daily evapotranspiration, for 15 days) and later exposed to a single episode of O3(200 ppb, 5 h day-1). Both stressors, applied alone or combined, affected ecophysiological responses. However, differential behaviour was observed between the species: under drought, photosynthetic capacity significantly decreased (-69% in comparison to controls), due to both stomatal and mesophyllic limitations only in Q. pubescens; the concomitant presence of drought and O3induced an ameliorative effect on photosystem II (PSII) performance during the fumigation in Q. cerris, whereas photochemical efficiency of PSII in light conditions of Q. pubescenswas highly impacted by O3treatment (-75%). These differences were confirmed by the different oxidative load showed by the species. Different trends and consequently different role of phytohormones was observed in relation to drought and O3. Under O3alone, similar spatial and functional correlations among these molecules were shown by the two species: ethylene emission values peaked at the end of the treatment (4-and 8-fold higher than controls, in Q. cerrisand Q. pubescens). In drought stressed-plants, phytohormones were differently involved in O3-induced signalling mechanisms: abscisic acid concentrations progressively increased starting to 2 and 5 h from the beginning of the exposure in Q. cerrisand Q. pubescens. Our results highlight a differential response of plants suffering from water withholding to a single O3episode compared to well-watered plants
Influence of drought stress on the ozone-induced signalling mechanisms of two Mediterranean tree species
Cotrozzi L.;Pellegrini E.;Remorini D.;Tonelli M.;Trivellini A.;Landi M.
;Guidi L.;Lorenzini G.;Massai R.;Vernieri P.;Nali C
2018-01-01
Abstract
The aim of the study was to investigate the influence of drought stress on the responses of two Mediterranean tree species, characterized by different drought-sensitivity, to a single pulse of ozone (O3). The behaviour of Quercus cerris(drought-sensitive) and Q. pubescens(mild-drought-sensitive) was evaluated in terms of ecophysiology and cross-talk responses among signalling molecules. Control plants maintained in well-watered and under filtered air conditions were compared with individuals subjected to drought (20% of the effective daily evapotranspiration, for 15 days) and later exposed to a single episode of O3(200 ppb, 5 h day-1). Both stressors, applied alone or combined, affected ecophysiological responses. However, differential behaviour was observed between the species: under drought, photosynthetic capacity significantly decreased (-69% in comparison to controls), due to both stomatal and mesophyllic limitations only in Q. pubescens; the concomitant presence of drought and O3induced an ameliorative effect on photosystem II (PSII) performance during the fumigation in Q. cerris, whereas photochemical efficiency of PSII in light conditions of Q. pubescenswas highly impacted by O3treatment (-75%). These differences were confirmed by the different oxidative load showed by the species. Different trends and consequently different role of phytohormones was observed in relation to drought and O3. Under O3alone, similar spatial and functional correlations among these molecules were shown by the two species: ethylene emission values peaked at the end of the treatment (4-and 8-fold higher than controls, in Q. cerrisand Q. pubescens). In drought stressed-plants, phytohormones were differently involved in O3-induced signalling mechanisms: abscisic acid concentrations progressively increased starting to 2 and 5 h from the beginning of the exposure in Q. cerrisand Q. pubescens. Our results highlight a differential response of plants suffering from water withholding to a single O3episode compared to well-watered plantsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
