Ozone symptoms in leaves of woody plants in open‐top chambers: ultrastructural and physiological characteristics

Article Article scientifique Article Ozone symptoms in leaves of woody plants in open‐top chambers: ultrastructural and physiological characteristics eng 2004-07-09 2004-07-09 author Gravano Elisabetta 510121 author Bussotti Filippo author Strasser Reto 25398 author Schaub Marcus author Novak Kristopher author Skelly John author Tani Corrado 620-633 10.1111/j.1399-3054.2004.00363.x 0031-9317 This study was carried out in the summer of 2001 at the Lattecaldo open‐top chamber research facility (Canton Ticino, southern Switzerland). The aim of this research study was to examine the behaviour of Fraxinus excelsior , Prunus avium and Viburnum lantana seedlings grown in charcoal‐filtered (CF) (∼ 50% of the ambient O 3 ) and non‐filtered (NF) (∼ 92% of the ambient O 3 ) air open‐top chambers. Investigations included the assessment of visible foliar symptom development, anatomical and ultrastructural analysis of symptoms, measurements of direct chlorophyll a fluorescence (fluorescence findings were processed by means of the JIP test) and leaf gas exchange measurements. The three species displayed different foliar symptoms. In F. excelsior , symptoms consisted of punctiform stipples with necrotic cells (hypersensitive response, HR), whereas, in P. avium and V. lantana , reddening developed, revealing the accumulation of anthocyanins. In V. lantana , symptoms appeared earlier than in the other species; in F. excelsior , symptoms developed more rapidly and led to premature leaf abscission. In F. excelsior , at least at the beginning, the onset of symptoms was combined with an enhanced photosynthetic efficiency (compensation mechanism), whereas, in P. avium and V. lantana , this efficiency progressively decreased. The fluorescence parameters most closely connected to ozone stress were as follows: a reduction in performance index (PI ABS ) and active reaction centres (RC/CS 0 ), and an increase in the variable fluorescence relative to 30 ms ( V I ) and of the dissipation processes. Dissipation is a form of defence mechanism against oxidative stress and is related to the role of the deactivated reaction centres (the silent centres) as well as anthocyanins. Symptom development correlated in all three species with the reduction in reaction centres. Symptomatic leaves had a lower net photosynthetic rate ( P n ). Net photosynthesis correlated with the reduction in V I , which suggests an accumulation of reduced plastoquinone, produced in the luminous phase of photosynthesis, which was not capable of reaching the dark phase reactions. Dewey 580 45 Département des sciences végétales 163 false Physiologia plantarum 121 4 5711c29c-aff7-4e84-b2fe-5ffb743ae74d Article (Published version) Restricted Gravano_PP_2004121620.pdf 2654354 application/pdf c8e729f7c2c40f0d9687acbce2df01e9d6c25590b28b916522059c72755c978a restrictedAccess Faculté des sciences / Section de biologie / Département des sciences végétales

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