Impatto degli stress biotici e abiotici sulla risposta fotochimica delle piante: analisi d'immagine dell'emissione di fluorescenza della clorofilla
Author(s)
Sighicelli, Maria
Date Issued
March 30, 2010
Type
Doctoral Thesis
Abstract
The plant defense response to biotic and abiotic stress involves morphological and physiological
alterations including changes in chloroplast structure and function. Chlorophyll fluorescence
emission kinetics from plants provide an indicator of plant photosynthetic performance.
Consequently, perturbations of photosynthetic metabolism significantly modify fluorescence
emission kinetic characteristics of plants. Several studies show that the photochemical efficiency of photosystems decreases with stress and the excess energy unused in photosynthesis and dissipated by non-photochemical processes increases. A rapid and noninvasive technique involving imaging of chlorophyll fluorescence is useful tool for early detection of plant responses to various stresses.
The analysis and monitoring of fungi disease caused by Phoma lingam on broccoli (Brassica
olearacea var. italica) and zinc accumulation in poplar (Populus x euramericana, clone I-214)
plants were investigated.
The plant photosynthetic performance was monitored by the portable Imaging-PAM fluorometer
(Walz, Germany). Chlorophyll fluorescence emission and photochemical parameters analysis in
plants at different days after inoculation with fungi and treatment with zinc compared with
uninfected and uncontaminated plants were carried out.
Moreover, a custom software for analysis of the photochemical parameters images has been
developed in order to gain a better understanding of the mechanisms that occur under metal stress.
Imaging analysis have been suited to visualize heterogeneity in plant response to stress.
The monitoring of biotic stress was confirmed. In fact, even if the symptoms are not evident, the
photochemical parameters ( changes in broccoli plants were observed. Further areas of infection
corresponding to disease development were evident only in imaging analysis.
The analysis of photochemical efficiency and non photochemical quenching in poplar plants show
differences both in response to time and in the capability to tolerate different zinc concentration.
Therefore, heterogeneity of images suggest that the pigment composition and concentration differ in cells from different regions of the leaf, contributing to spatial differences in photochemical activity and changes in the antenna down-regulation.
Additional information
Dottorato di ricerca in Ecologia forestale
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