Assaying for superoxide dismutase activity: Some large consequences of minor changes in conditions

137

The adverse effects of arsenic (As) toxicity on seedling growth, root and shoot anatomy, chlorophyll and carotenoid contents, root oxidizability (RO), antioxidant enzyme activities, H 2 O 2 content, lipid peroxidation and electrolyte leakage (EL%) in common bean (Phaseolus vulgaris L.) were investigated. The role of exogenous nitric oxide (NO) in amelioration of As-induced inhibitory effect was also evaluated using sodium nitroprusside (100 μM SNP) as NO donor and 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (200 μM PTIO) as NO scavenger in different combinations with 50 μM As. Asinduced growth inhibition was associated with marked anomalies in anatomical features, reduction in pigment composition, increased RO and severe perturbations in antioxidant enzyme activities. While activity of superoxide dismutase and catalase increased, levels of ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase decreased significantly and guaiacol peroxidase remained normal. The over-accumulation of H 2 O 2 content along with high level of lipid peroxidation and electrolyte leakage indicates As-induced oxidative damage in P. vulgaris seedlings with more pronounced effect on the roots than the shoots. Exogenous addition of NO significantly reversed the As-induced oxidative stress, maintaining H 2 O 2 in a certain level through balanced alterations of antioxidant enzyme activities. The role of NO in the process of amelioration has ultimately been manifested by significant reduction of membrane damage and improvement of growth performance in plants grown on As + SNP media. Onset of oxidative stress was more severe after addition of PTIO, which confirms the protective role of NO against Asinduced oxidative damage in P. vulgaris seedlings.

Section: Antioxidant Enzyme Assaysmentioning

confidence: 99%

Arsenic-induced oxidative stress in the common bean legume, Phaseolus vulgaris L. seedlings and its amelioration by exogenous nitric oxide

Talukdar

2012

137

“…Superoxide dismutase activity was estimated in terms of inhibition of the photochemical reduction of Nitroblue tetrazolium (NBT) as per the procedure of Beyer and Fridovich (1987). The reaction mixture (3 ml) consisted of 50 mM phosphate buffer (pH 7.8) and 0.1 mM EDTA, 14.3 mM methionine, 82.5 mM NBT and 2.2 mM riboflavin.…”

Section: Estimation Of Superoxide Dismutase Activitymentioning

confidence: 99%

In vitro selection and characterization of polyethylene glycol (PEG) tolerant callus lines and regeneration of plantlets from the selected callus lines in sugarcane (Saccharum officinarum L.)

Srinath

Ftz

2013

A system for in vitro selection of drought tolerant callus lines in sugarcane was developed. High molecular weight PEG was used as selective agent. Selected callus line grew better than non-selected callus when grown on different concentrations of PEG. The activity of antioxidant enzymes like CAT, POX, APX and SOD were high in selected callus than in non-selected callus. Osmolytes like proline and ascorbic acid were at higher levels in selected callus than in nonselected callus, however at higher concentrations (20-30 %) of PEG, levels of proline and ascorbic acid decreased. The frequency of organogenesis and number of plantlets decreased in selected callus than in non-selected callus. The results can be used for in vitro screening and manipulations of sugarcane for improvement of drought tolerance

“…Superoxide dismutase activity was assayed by monitoring the inhibition of photochemical reduction of nitro blue tetrazolium salt (NBT), as described by Beyer and Fridovich (1987). One unit of SOD activity was defined as the amount of enzyme required to cause 50 % inhibition in the reduction of NBT, monitored at 560 nm, under assay conditions.…”

Section: Enzyme Assaysmentioning

confidence: 99%

Responses to drought induced oxidative stress in five finger millet varieties differing in their geographical distribution

Bhatt

Negi

Sharma

et al. 2011

The study presents the impact of drought stress on five finger millet varieties (PR202, VL146, VL315, PES400 and VR708), representing contrasting areas of Indian sub-continent. Drought stress induced increase in the activity of superoxide dismutase, ascorbate peroxidase and glutathione reductase was higher in PR202 and VL315, while the activity was lower in the varieties PES400 and VR708. Ascorbate peroxidase : superoxide dismutase ratio, which is a crucial factor in alleviating drought stress, was higher in varieties PR202 and VL315, whilst the varieties PES400 and VR708 exhibited a lower ratio under stress. The variety PES400 recorded maximum stress induced damage, as indicated by higher accumulation of malondialdehyde and hydrogen peroxide; whereas the variety PR202 recorded least stress induced cytotoxic damage. The results clearly indicate that better drought tolerance of the variety PR202 is positively related to the capacity of its antioxidant system to scavenge reactive oxygen species, resulting in a reduced incidence of oxidative damage. Ascorbate peroxidase : superoxide dismutase ratio is found to be a critical factor governing the stress tolerance potential of different varieties. Therefore, varieties PR202 and VL315 were found to be tolerant while PES400 was susceptible to drought stress.