Effect of salinity on antioxidant enzymes in calli of the halophyte Nitraria tangutorum Bobr.

Abstract

Nitraria tangutorum Bobr., a typical desert halophyte, plays an important ecological role because of its superior tolerance to severe drought and high salinity. Very little is known about the physiological adaptative mechanism of this species to environmental stresses. The aim of this study was to investigate the changes of antioxidant enzyme activities and the regulatory mechanism of ascorbate peroxidase (APX) activity in the calli from Nitraria tangutorum Bobr. after treatment with different NaCl concentrations. The activities of superoxide dismutase (SOD) and catalase (CAT) significantly increased in the calli treated with NaCl, while the peroxidase activity decreased. APX activity was also elevated significantly in response to NaCl, but the increase was partly abolished by H 2 O 2 scavenger dimethylthiourea (DMTU). Furthermore, the excitatory effect of salinity on APX could be alleviated by the addition of exogenous CAT and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor diphenylene iodonium, indicating that the modulation of the APX activity in Nitraria tangutorum Bobr. calli might be associated with NADPH oxidase-dependent H 2 O 2 generation. Measurement and analysis using fluorescent dye 2 0 ,7 0 -dichlorodihydrofluorescein diacetate showed the increase of H 2 O 2 content in salinity-treated calli. The investigation of NADPH-dependent O 2 -production in plasma membrane (PM) vesicles isolated from Nitraria tangutorum Bobr. calli revealed that salinity treatment stimulated NADPH oxidase activity. In conclusion, these results suggest that the higher activities of antioxidant enzymes play an important role in the salt tolerance of Nitraria tangutorum Bobr. calli and that the extracellular production of H 2 O 2 , depending on the excitation of PM NADPH oxidase, is responsible for enhancing the APX activity in Nitraria tangutorum Bobr. calli under salinity stress.

Oxidative Stress Studies in Plant Tissue Culture

“…CAT is also important in the removal of H2O2 generated in peroxisomes during the -oxidation of fatty acids, photorespiration, and purine catabolism (Ahmad et al, 2008;Gill and Tuteja, 2010;Karuppanapandian et al, 2011). Various abiotic stresses induced CAT activities under in vitro conditions in different plants, including hyperhydricity, salinity, drought, and gamma radiation (Saher et al, 2004;Chakrabarty et al, 2005;Rahnama and Ebrahimzadeh, 2005;Dewir et al, 2006Niknam et al, 2006Erturk et al, 2007;Dasgupta et al, 2008;Sivritepe et al, 2008;Shehab et al, 2010;Yang et al, 2010;Zamora et al, 2010;El-Beltagi et al, 2011;Sen and Alikamanoglu, 2011;Helaly and El-Hosieny, 2011;Patade et al, 2012) in contrast, Fe-deficiency stress reduced activity of CAT (Lombardi et al, 2003;Mohamed and Aly, 2004). CAT activities also induced in Medicago sative clones, which were improved with in vitro selection method, under PEG-treatment (Safarnejad, 2004).…”

“…The Mn-SOD is resistant to both inhibitors; Cu/Zn-SOD is sensitive to both inhibitors whereas; Fe-SOD is resistant to KCN and sensitive to H2O2 (Ahmad et al, 2008;Gill and Tuteja, 2010;Karuppanapandian et al, 2011). There have been many reports of the increased activities of SOD under abiotic stresses induced with tissue culture techniques in a wide range of plant species, including heavy metals, such as Al, Cd, Cr, and Cu, hyperhydricity, salinity, gamma radiation, and drought (Gallego et al, 2002;Saher et al, 2004;Dewir et al, 2006;Israr et al, 2006;Erturk et al, 2007;Dasgupta et al, 2008;Sivritepe et al, 2008;Gupta and Prasad, 2010;Shehab et al, 2010;Yang et al, 2010;El-Beltagi et al, 2011;Helaly and El-Hosieny , 2011;Lokhande et al, 2011;Sen and Alikamanoglu, 2011;Xu et al, 2011;Patada et al, 2012) on the other hand, Fe-deficiency stress reduced activity of SOD (Lombardi et al, 2003). Advanced-antioxidant defense systems play an important role in plants not only to tolerate environmental stress but also to improve plants against these stresses.…”

Copper-induced oxidative stress in Alternanthera philoxeroides callus

“…Recent researches concerning heavy metals and other stresses have focused on natural growth plants (Gonnelli et al 2001;Shi et al 2003;Lou et al 2004;Chatzissavvidis et al 2008;Cui et al 2010;Lokhande et al 2010;Xu et al 2010). To our knowledge, very little is known about the toxicity of heavy metals and other stress factors in callus (Fornazier et al 2002;Taddei et al 2007;Sun et al 2010;Yang et al 2010) and no work has, so far, been carried out to research physiological changes under copper stress in A. philoxeroides callus.…”

Pathways of ROS homeostasis regulation in Mesembryanthemum crystallinum L. calli exhibiting differences in rhizogenesis

“…Similarly, an increase in catalase activity in salt-stressed callus tissues was found previously in halophyte Nitraria tangutorum Bobr. (Yang et al 2010) and in sugar cane cells (Patade et al 2011). Callus cultured on CIM medium, without NaCl, was characterized by a high amount of betacyanins (Fig.…”