After treatment with a pulse of ozone (120 ppb, 4 h), enzymatic activities involved in the detoxification of reactive oxygen species [superoxide dismutase (SOD), total peroxidase (PX), ascorbate peroxidase (APX), syringaldazine peroxidase (SPX) and guaiacol peroxidase (GPX)] were determined in the primary leaves of two cultivars of bean (Phaseolus vulgaris), which on the basis of macroscopic responses were designated ozone-sensitive (cv. Pinto) and ozone-resistant (cv. Groffy). Although slightly higher in the sensitive cultivar, all PX activities were found to be at nearly comparable levels in the untreated plants of both cultivars; hovewer for SOD, constitutive levels were about twice as high in the resistant cultivar. The response to ozone developed rather slowly, being maximal after 48-96 h. Exposure to ozone caused a large increase of SOD and PX activities in the sensitive Pinto, and smaller variations in the resistant Groffy. The largest variations (up to 7-11 fold increases) were observed for APX, SPX and SOD activities in Pinto. We conclude that the induction of antioxidant enzymes does not represent a major defence mechanism against ozone in bean, but appears to be a secondary consequence of ozone injury.
Peroxidase and superoxide dismutase activities in bean in response to ozone
NALI, CRISTINA;LORENZINI, GIACOMO
1997-01-01
Abstract
After treatment with a pulse of ozone (120 ppb, 4 h), enzymatic activities involved in the detoxification of reactive oxygen species [superoxide dismutase (SOD), total peroxidase (PX), ascorbate peroxidase (APX), syringaldazine peroxidase (SPX) and guaiacol peroxidase (GPX)] were determined in the primary leaves of two cultivars of bean (Phaseolus vulgaris), which on the basis of macroscopic responses were designated ozone-sensitive (cv. Pinto) and ozone-resistant (cv. Groffy). Although slightly higher in the sensitive cultivar, all PX activities were found to be at nearly comparable levels in the untreated plants of both cultivars; hovewer for SOD, constitutive levels were about twice as high in the resistant cultivar. The response to ozone developed rather slowly, being maximal after 48-96 h. Exposure to ozone caused a large increase of SOD and PX activities in the sensitive Pinto, and smaller variations in the resistant Groffy. The largest variations (up to 7-11 fold increases) were observed for APX, SPX and SOD activities in Pinto. We conclude that the induction of antioxidant enzymes does not represent a major defence mechanism against ozone in bean, but appears to be a secondary consequence of ozone injury.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
