Abstract
<p>Chlorine is one of the ions contributing to salinity, despite being an essential micronutrient. Cl<sup>-</sup> absorption takes place more easily than other nutrients so, the toxic effects of chlorine on the growth has considered rather than its scarcity. Salt stress can ultimately leads to oxidative stress through ROS increase and antioxidant defense system is induced. Therefore, in this study the effect of different concentration of chlorine in irrigation water on the expression of manganese superoxide dismutase was investigated as an indicator of antioxidant defense system activation. Seedlings of tobacco were treated with different concentrations, i.e. 2, 4, 8 mM of CaCl<sub>2</sub>. Evaluation of Mn-SOD isoenzyme gene expression was performed using RT-qPCR (quantitative reverse transcription PCR) at 0, 3, 6 and 12 hours after treatment. The results showed Mn-SOD gene transcription increased after 3 h treatment with 8 mM CaCl<sub>2</sub> and peaked at 6 hours. Based on the observed changes, concentrations of calcium chloride greater than 8 mM in water used for irrigation of tobacco causes stress that results in activation of antioxidant response.</p>
Highlights
Abiotic stresses including drought, salinity, cooling, heating and heavy metal exposure are the major threats to plants and, to sustainable agriculture
There were no significant differences between treated samples exposed to concentrations of 2, 4 and 8 mM calcium chloride
Three hours after the initiation of Cl- stress, a significant increase in manganese superoxide dismutase (Mn-superoxide dismutase (SOD)) mRNA expression was observed in plants treated with 8 mM calcium chloride
Summary
Salinity, cooling, heating and heavy metal exposure are the major threats to plants and, to sustainable agriculture. Together, they decrease cereal production by more than 50 % across the world (Tuteja, 2007). Salinity is one of the key stressors in the water or soil of arid and semi-arid regions and is able to limit growth and productivity of plants (Koca et al, 2007; Allakhverdiev et al, 2000). The rate of water evaporation and precipitation of salt are determinants of soil salinity. The process of water absorption by plant roots is impacted by high salinity via reduction in soil water osmotic potential, the outcome of which.
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