The effect of acute O-3 exposure (5 h at 150 ppb) on photosynthetic electron transport and the thylakoid polypeptide pattern has been studied in 2-month-old cuttings of two poplar clones (Populus deltoides x maximowiczii clone Eridano and P. x euramericana clone I-214), known for their differential response to O-3 in terms of visible symptoms. The more sensitive Eridano developed severe blackish bifacial necrosis concentrated in the interveinal areas of the basal and intermediate leaves, while in the less sensitive I-214 clone, visible symptoms were slight or entirely absent. A generalized, significant decrease in leaf pigment content was shown by both of the stressed clones, although the decline in p-carotene content was much more marked in Eridano than in I-214, Activation of the xanthophyll cycle was not detected in either clone. In both clones, immunoblot analysis of the thylakoid proteins showed a decrease in the levels of all the PSII polypeptides tested following O-3 exposure, whereas the PsaA/B protein in the PSI core was more severely affected in Eridano than in I-214, No changes in the chloroplast structure could be seen on electron microscopic study in either clone. The only visible difference was a great accumulation of starch grains in Eridano, All of these results suggest that O-3 exposure induces alterations in the photosynthetic apparatus in both poplar clones, Eridano being affected to a greater extent than I-214.
Differential sensitivity to ozone in two poplar clones.Analysis of thylakoid pigment-protein complexes
BALDAN, BARBARA;
2000
Abstract
The effect of acute O-3 exposure (5 h at 150 ppb) on photosynthetic electron transport and the thylakoid polypeptide pattern has been studied in 2-month-old cuttings of two poplar clones (Populus deltoides x maximowiczii clone Eridano and P. x euramericana clone I-214), known for their differential response to O-3 in terms of visible symptoms. The more sensitive Eridano developed severe blackish bifacial necrosis concentrated in the interveinal areas of the basal and intermediate leaves, while in the less sensitive I-214 clone, visible symptoms were slight or entirely absent. A generalized, significant decrease in leaf pigment content was shown by both of the stressed clones, although the decline in p-carotene content was much more marked in Eridano than in I-214, Activation of the xanthophyll cycle was not detected in either clone. In both clones, immunoblot analysis of the thylakoid proteins showed a decrease in the levels of all the PSII polypeptides tested following O-3 exposure, whereas the PsaA/B protein in the PSI core was more severely affected in Eridano than in I-214, No changes in the chloroplast structure could be seen on electron microscopic study in either clone. The only visible difference was a great accumulation of starch grains in Eridano, All of these results suggest that O-3 exposure induces alterations in the photosynthetic apparatus in both poplar clones, Eridano being affected to a greater extent than I-214.
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
