Effect of salinity on antioxidant system in rice cultivars
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Date
2008
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Publisher
CCSHAU
Abstract
Effect of salinity was studied on osmoregulation, enzymes and
metabolites of reactive oxygen species (ROS) scavenging pathway in leaves and
roots of Oryza sativa. For this, six cultivars of rice, three each salt-tolerant
(Pokkali, CSR-1 and CSR-10) and salt-sensitive (Basmati-370, IR-28 and
MI-48) were taken. The relative water content and osmotic potential decreased
upon salinization in all the cultivars, however, the magnitude of reduction was
more in salt-sensitive cultivars with increase in salt concentration. Na+/K+
also increased with increasing salt stress in all the cultivars, but the increase
was much higher in the salt-sensitive cultivars than salt-tolerant cultivars.
Similarly, the production of toxic reactive oxygen species (viz. .O2- and H2O2)
and malondialdehyde content (MDA), which is an indicator of cell-membrane
damage also increased in all the cultivars with higher level of increment in the
salt-sensitive cultivars than salt-tolerant cultivars in both the tissues viz.
leaves and roots. The salt-stress had differential effects on the antioxidant
enzyme activities in leaves and roots of salt-sensitive and salt-tolerant
cultivars. There was enhancement in the activities of superoxide dismutase and
glutathione reductase in all the tolerant cultivars while the activities of these
enzymes decreased with increasing salinity in the sensitive cultivars.
Salt-stress induced the activities of catalase and peroxidase in all the cultivars
but the magnitude of increase was more pronounced in sensitive cultivars than
tolerant cultivars. Ascorbate peroxidase activity increased in both the tissues of
the salt-sensitive cultivars and decreased in the salt-tolerant cultivars.
However, the basal level was much higher in the tolerant cultivars. Contrarily,
GPX activity declined in roots and leaves of sensitive cultivars but remained
unaltered in salt-tolerant cultivars upon exposure to salt-stress. The tolerant
cultivars had higher ratio of glutathione reduced (GSH)/glutathione oxidized
(GSSG). Ascorbic acid content increased in leaves of tolerant cultivars while
reduced in both leaves and roots of sensitive cultivars under saline condition.
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Keywords
Storage, Fruits, Sugar, Acidity, Reducing sugars, Productivity, Vitamins, Vegetables, Irrigation, Beverages