title: The ozone-like syndrome in durum wheat (Triticum durum Desf.): Mechanisms underlying the different symptomatic responses of two sensitive cultivars.
abstract: Colombo and Sculptur are two modern durum wheat cultivars that, in previous studies, proved to be very sensitive to ozone injury in terms of eco-physiological parameters and significant grain yield loss. Nevertheless, their response regarding leaf visible symptoms was very different; Sculptur showed almost no symptoms, even after several weeks of ozone exposure, whereas Colombo showed in a few weeks typical ozone-like symptoms (chlorotic/necrotic spots). The mechanisms underlying this different response has been studied with a biochemical and microscopical approach. Plants were grown in Open-Top Chambers (OTCs) and exposed to charcoal filtered and ozone enriched air. Flag leaves were analyzed at two phenological stages (pre- and post-anthesis). At pre-anthesis the ascorbate pool was significantly lower in Colombo, which also underwent an increase in the oxidized glutathione content and abundant H2O2deposition in mesophyll cells around the substomatal chamber. No or scarce H2O2was found at both phenological stages in ozone exposed leaf tissues of Sculptur, where stomata appeared often closed. In this cultivar, transmission electron microscopy showed that chloroplasts in apparently undamaged mesophyll cells were slightly swollen and presented numerous plastoglobuli, as a result of a mild oxidative stress. These results suggest that Sculptur leaves remains symptomless as a consequence of the higher content of constitutive ascorbate pool and the synergistic effect of stomata closure. Instead, Colombo shows chlorotic/necrotic symptoms because of the lower ROS (Reactive Oxygen Species) scavenging capacity and the less efficient stomata closure that lead to severe damages of groups of the mesophyll cells, however leaving the surrounding photosynthetic tissue functional.
authors.affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CREA), Unità di ricerca per i processi dell'industria agroalimentare, Via G. Venezian 26, 20133 Milan, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Picchi
authors.affiliation: Department of Agricultural and Environmental Sciences - Production, Land, Agroenergy, University of Milan, Via Celoria 2, Milano, Italy.
authors.forename: Robert
authors.initials: R
authors.lastname: Monga
authors.affiliation: Department of Mathematics and Physics, Catholic University of Brescia, Via dei Musei 41, Brescia, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Marzuoli
authors.affiliation: Department of Mathematics and Physics, Catholic University of Brescia, Via dei Musei 41, Brescia, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Gerosa
authors.affiliation: Department of Agricultural and Environmental Sciences - Production, Land, Agroenergy, University of Milan, Via Celoria 2, Milano, Italy. Electronic address: franco.faoro@unimi.it.
authors.forename: Franco
authors.initials: F
authors.lastname: Faoro
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D014908:Triticum / Q000166:cytology / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D010126:Ozone; D005978:Glutathione; D001205:Ascorbic Acid
keywords: Cell death; Chloroplasts; Oxidative stress; Ozone; Stomata; Wheat