Early Responses to Acute Ozone Exposure in Two Fagus Sylvatica Clones Differing in Xeromorphic Adaptations: Photosynthetic and Stomatal Processes, Membrane and Epicuticular Characteristics |
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Authors: | Elena Paoletti Cristina Nali Giacomo Lorenzini |
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Institution: | (1) Istituto Protezione Piante-Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy;(2) Dipartimento G. Scaramuzzi, Università di Pisa, Via del Borghetto 80, Pisa, Italy |
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Abstract: | Two Fagus sylvatica L. clones were used to investigate the early responses to acute O3 exposure (150 nL L−1, i.e., 1.35× ambient hourly peak in rural Italy) and whether xeromorphic adaptations affect gas exchange, membrane, and epicuticular
responses. One clone originated in a wet and temperate climate in Central Italy (Tuscany); the other clone originated in a
warmer and drier climate in the southern-most part of the F. sylvatica distribution (Sicily). Because of higher base gas exchange rates, the most negative effects of O3 exposure (gas exchange impairment, uncoupling between net photosynthesis and stomatal conductance, increased membrane lipid
peroxidation) were found in the southern clone. Xeromorphic adaptations (higher epicuticular waxes and stomatal density, lower
leaf wettability and size) were found in this clone. Our results suggest that xeromorphism may increase O3 sensitivity in species not adapted to face water stress, like the mesophilic F. sylvatica, when experiments are carried out with full irrigation. We present evidence describing the relationship between gas exchange
and number and status of stomata. Stomatal density and the structural damage to stomata resulting from O3 exposure did not affect gas exchange: In fact, non-stomatal limitations to photosynthesis prevailed over stomatal limitations. |
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Keywords: | A/Ci curves Beech Chlorophyll fluorescence Drop contact angle Fagus sylvatica Lipid peroxidation Membrane permeability Xeromorphism |
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