Exogenous application of mannitol and thiourea regulates plant growth and oxidative stress responses in salt-stressed maize (Zea maysL.)

Abstract

The mechanism of growth amelioration in salt-stressed maize (Zea mays L. cv., DK 647 F1) by exogenously applied mannitol (M) and thiourea (T) was investigated. Maize seedlings were planted in pots containing perlite and subjected to 0 or 100 mM NaCl in full strength Hoagland's nutrient solution. Two levels of M (15 and 30 mM) or T (3.5 and 7.0 mM) were sprayed to the leaves of maize seedlings 10 days after germination. Salinity stress caused considerable reduction in plant dry biomass, chlorophyll content, and relative water content in the maize plants. However, it increased the activities of catalase (CAT; EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), and polyphenol oxidase (PPO; EC 1.10.3.1), and levels of hydrogen peroxide (H 2 O 2 ) and electrolyte leakage, but it did not change peroxidase (POD; EC 1.11.1.7) activity. Foliar application of M or T was found to be effective in checking salt-induced shoot growth inhibition. Exogenously applied M or T reduced the activities of CAT, SOD, POD, and PPO in the salt-treated maize plants compared to those in the plants not fed with these organic compounds. Salinity increased Na ' contents but decreased those of K ' , Ca 2 ' , and P in the leaves and roots of the maize plants. Foliar-applied M or T increased the contents of K ' , Ca 2 ' , and P, but decreased that of Na ' in the salt-stressed maize plants with respect to those of the salt-stressed plants not supplied with mannitol or thiourea. Mannitol was found to be more effective than thiourea in improving salinity tolerance of maize plants in terms of growth and physiological attributes measured in the present study.

Effect of sodium carbonate-induced salinity–alkalinity on some key osmoprotectants, protein profile, antioxidant enzymes, and lipid peroxidation in two mulberry (Morus alba L.) cultivars

“…Salvadora persica (Ramoliya et al 2004), Olea europea (Chartzoulakis et al 2002), and Simmondsia chinesis (Roussos et al 2006). However, growth inhibition in a plant due to salt or alkali stress could occur due to regulation of a multitude of physiological and biochemical processes such as water relations (Munns 2002;Meloni & Martinez 2009;Ahmad et al 2012b), ion transport and accumulation (Hasegawa et al 2000), photosynthesis (Dubey 2005;Ashraf et al 2008), accumulation of osmoprotectants (Ashraf & Foolad 2007;Koyro et al 2012;Katare et al 2012), synthesis of antioxidant enzymatic and nonenzymatic molecules (Mittler 2002;Patade et al 2011;Bano et al 2013;Kaya et al 2013;Rasool et al 2013), synthesis of plant growth regulators (Ashraf et al 2010), mineral nutrient metabolism (Marschner 1995), and many others. One of the most important biochemical responses of plants to abiotic stresses is overproduction of different types of compatible solutes such as proline, glycine betaine, sugars, soluble proteins, amino acids, etc.…”

“…Plants tend to counteract reactive oxygen species produced by stress Bano et al 2013;Kaya et al 2013). They synthesize both enzymatic and nonenzymatic antioxidants in high amounts for this purpose .…”

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

“…However, when plants are exposed to stress over an extended period of time, they accumulate more ROS than they eliminate. As soon as the balance is broken, the overaccumulation of ROS in plants leads to significant damage to the membrane system of plants from a lipid peroxidation reaction, which can increase permeability and conductivity (Gallego et al 1996;Chaoui et al 1997;Kaya et al 2013). Although plant growth, chlorophyll content, stomata opening, transpiration, and photosynthesis have been reported to be inhibited by Cd in nutrient solutions (Jiang & Li 1992;Baryla et al 2001;Drążiewicz & Baszyński 2005;Sun et al 2005), there have also been reports that Cd treatments had no effect on photosynthesis or growth (Greger & Lindberg 1986;Haag-Kerwer et al 1999;Li et al 2005;Zhou & Qiu 2005), and that N was possibly a bioactive signaling molecule in plant responses to heavy metal stress (Hassan et al 2005;Floryszak-Wieczorek et al 2006;Grün et al 2006;Arasimowicz & Floryszak-Wieczorek 2007).…”

Rhizosphere and endophytic bacteria for induction of salt tolerance in gladiolus grown in sodic soils

“…However, most plant species do not produce sufficient antioxidants to fulfill their growth requirements under salt stress. Therefore, bioinoculation induces salt tolerance by increasing the activity of antioxidant enzymes (SOD, PO, and catalase) and organic solutes like proline (Kaya et al 2013). The bio-inoculation also enhanced the defense mechanism of the plants due to the elevated level of the enzyme activity in the host plants (Ashraf & Foolad 2007).…”