c7.7.50 – Dynamics and cause-effect relationships between ethylene emission, H2O2 accumulation and some physiological and molecular responses to ambient O3 concentrations in two differently O3-sensitive poplar clones

Di Baccio D (1), Castagna A (2), Cocozza C (3), Sebastiani L (1), Ranieri A (2), Tognetti R (3)

(1) BioLabs, Scuola Superiore Sant’Anna, Piazza Martiri della Libertà 33, I-56127 Pisa, Italy; (2) Department of Agricultural Chemistry and Biotechnology, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy; (3) EcoGeoFor Lab – Dipartim
Collocazione: c7.7.50 – Tipo Comunicazione: Poster
7° Congresso SISEF *
Sessione 7: “Poster” *

Contatto: Daniela Di Baccio (dibaccio@sssup.it)

Abstract: Increasing global background concentrations of tropospheric ozone (O3) are expected to affect both crops and forest ecosystems negatively. In the Mediterranean area, O3 easily reaches high concentrations in summer due to intense solar radiation, high temperature and very dry conditions, which favour atmospheric photochemical activity. Tropospheric O3 is believed to be the most important phytotoxic air pollutant in industrialised countries and one of the major anthropogenic stresses contributing to forest decline, the dramatic phenomenon affecting forest areas in Europe and North America. Recent results from the Italian 10 CONECOFOR programme showed in fact that AOT40 values are around 5-10 ppm h on the Alps, 11 usually higher than the critical levels for forests across the peninsula (10 ppm h), and very high in 12 the South of Italy (26 ppm h). Two poplar clones (Populus deltoides x maximowiczii, clone Eridano, O3-sensitive, and P. x euramericana, clone I-214, O3-resistant), known for their differential responses to O3 in terms of development of leaf injuries have been used as model plants to understand the physiological, biochemical and molecular basis of plant reactions to ambient O3 concentrations typical of urban areas (60 nl l-1 O3, 15 days, 5 h a day). Due to the different trend of O3-induced ethylene emission by the two clones, indicative of a different extent of ongoing accelerated senescence, a time-course study is in progress to understand the dynamics and the cause-effect relationships between some physiological and bio-molecular responses to these realistic doses of O3 up to 15 days. More in details, leaf gas exchange analysis will indicate whether the two clones differ in O3 uptake dynamics and, together with chlorophyll a fluorescence analysis, will give information on photosynthetic performance during O3 exposure. The progression of H2O2 accumulation, as a marker of oxidative stress, will be related to the onset of antioxidant shelter, estimated by measuring ascorbate and glutathione redox states and related enzyme activities and gene expression levels. The collected data will represent another step to unravel the plant adaptive mechanisms of response triggered by O3 uptake.

Citazione: Di Baccio D , Castagna A , Cocozza C , Sebastiani L , Ranieri A , Tognetti R (2009). Dynamics and cause-effect relationships between ethylene emission, H2O2 accumulation and some physiological and molecular responses to ambient O3 concentrations in two differently O3-sensitive poplar clones . 7° Congresso Nazionale SISEF, Isernia – Pesche (IS), 29 Set – 03 Ott 2009, Contributo no. #c7.7.50