Effects of optimal and supra-optimal salinity stress on antioxidative defence, osmolytes and in vitro growth responses in Sesuvium portulacastrum L.

Abstract

The effect of optimal and supra-optimal concentrations (0, 200, 400 or 600 mM) of NaCl on the growth, osmotic adjustment and antioxidant enzyme defence was studied in the in vitro cultures of Sesuvium portulacastrum. A significant increase in growth, tissue water content (TWC) and fresh to dry weight ratio (FW/DW) was observed in the shoots exposed to 200 mM salt. Minimum damage to the membrane in terms of low relative electrolytic leakage (REL) and malondialdehyde (MDA) content and better osmotic adjustment at 200 mM salt stress was coupled with the higher accumulation of sodium ions and total soluble sugars as against low proline and glycine betaine contents. A fine tuning of antioxidant enzyme activities (superoxide dismutase, catalase and ascorbate peroxidase) was also found to be responsible for the optimum growth of shoots. In contrast, sub-optimal (0 mM) and supra-optimal concentrations (400-600 mM) of NaCl significantly affected the growth, water status and increased the REL as well as MDA content of the shoots due to the accumulation of toxic concentrations of saline ions. The highest accumulation of proline and glycine betaine in addition to antioxidant enzyme activities exhibited higher osmotic adjustment and survival of the shoots under sub-or supra-optimal concentrations of NaCl as a penalty to reduced growth.

Oxidative Stress Studies in Plant Tissue Culture

“…Generally known that APX has a higher affinity for H2O2 (μM range) than CAT and POX (mM range) and it may have a more crucial role in the management of ROS during stress (Gill and Tuteja, 2010;Karuppanapandian et al, 2011). Lokhande et al, (2011) observed that under NaCl-induced oxidative stress conditions, APX enzyme activities increased but CAT enzyme activities decreased in Sesuvium portulacastrum tissue cultures. Mohamed and Aly, (2004) reported that Fe-deficiency stress reduced activity of APX in Borage officinalis tissue culture.…”

“…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.…”

“…As I previously mentioned plant tissue culture techniques are performed under aseptic and controlled environmental conditions. In addition, this technique allows for the study of large plant population, stress treatment of large population in a limited space and short period of time, and homogeneity of stressor application (Sakthivelu et al, 2008, Lokhande et al, 2011. Plant tissue culture techniques, because of these advantages, have vast potential for various applications both plant science and commercially, such as producing large numbers of identical individuals via micropropagation using meristem and shoot cultures, producing secondary products in liquid cultures, crossing distantly related species by protoplast fusion and regeneration of the novel hybrid, production of dihaploid plants from haploid cultures to achieve homozygous lines more rapidly in breeding programs, using tissue cultures as a model for inducing oxidative stress via different stressor agents and improving plants against abiotic stresses using in vitro selection techniques (www.liv.ac.uk).…”

“…Investigating these responses is difficult under field conditions, but plant tissue culture techniques are performed under aseptic and controlled environmental conditions. These advantages of plant tissue culture allow various opportunities for researcher to study the unique and complex responses of plants against environmental stresses (Sakthivelu et al, 2008, Lokhande et al, 2011.…”

Growth, sodium uptake and antioxidant responses of coastal plants differing in their ecological status under increasing salinity

“…It was found that the activities of major antioxidant enzymes such as SOD, APX, CAT and POX can be significantly increased in some halophytes. For example, in Sesuvium portulacastrum, 1 M NaCl treatment increased SOD, APX, CAT enzyme activities (Lokhande et al 2011). On the other hand, no significant change or a decrease in activity of some antioxidant enzymes were reported in Crithmum maritimum (Ben Hamed et al 2007).…”