Activities of antioxidant enzymes and photosynthetic responses in tomato pre-treated by plant activators and inoculated by Xanthomonas vesicatoria
The activities of antioxidant enzymes and photosynthetic responses were investigated in tomato ( Lycopersicon esculentum L. var.) pre-treated by plant activators and inoculated by Xanthomonas vesicatoria. Plants were sprayed with acibenzolar-S-methyl, ASM [Bion ® 50 WG (0.2 g l −1)] and aqueous extr...
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Published in | Physiological and molecular plant pathology Vol. 68; no. 4; pp. 198 - 208 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier India Pvt Ltd
01.04.2006
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Subjects | |
Online Access | Get full text |
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Summary: | The activities of antioxidant enzymes and photosynthetic responses were investigated in tomato (
Lycopersicon esculentum L. var.) pre-treated by plant activators and inoculated by
Xanthomonas vesicatoria. Plants were sprayed with acibenzolar-S-methyl, ASM [Bion
® 50
WG (0.2
g
l
−1)] and aqueous extract from dry necrotic tissue flour (VLA) of ‘Lobeira’ (
Solanum lycocarpum) bush. Four days later, the plants were challenged with a virulent strain of
X. vesicatoria, under greenhouse conditions. Tomato leaves were then assessed to determine the activities of the main antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and ascorbate peroxidase (APX). A reduction of bacterial leaf spot severity was observed in plants treated by ASM (49.3%) and VLA (31.4%), without any
in vitro inhibitory activity over the pathogen. Controls showed decreases in CO
2 assimilation, transpiration, photosynthetic rates, and stomatal conductance. Water use efficiency and carboxylation efficiency were strongly affected in ASM- and VLA-treated, in comparison to controls and healthy plants. The tested substances induced increases in SOD and CAT activities in a delayed enzymatic response typical in compatible plant–pathogen interactions. Measured at daily intervals, activities of APX and POX were significantly
(
ρ
⩽
0.05
)
higher in treated plants than in controls, except for APX in ASM-treated plants where no difference was found when compared to controls. Only POX was clearly induced at the earlier stages after spraying the tomato plants with ASM or VLA. Our results suggest that late increases in antioxidant enzyme activities may play a role in mitigating oxidative damage in restoring the photosynthetic imbalance imposed by the expansion of bacterial lesions. |
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ISSN: | 0885-5765 1096-1178 |
DOI: | 10.1016/j.pmpp.2006.11.001 |