In situ and in vitro senescence induced by KCl stress: nutritional imbalance, lipid peroxidation and antioxidant metabolism

Abstract

Sunflower (Helianthus annuus L. cv. SH222) plants and calli were exposed to KCl stress for three weeks. Calli were more tolerant to KCl than plants. KCl stress decreased NO(-)(3), Mn, Fe and B levels in whole plants and P, Ca and Mg in shoots. NO(-)(3), P, Ca, Mg, Mn, and B levels decreased in 100 mM-stressed calli. Chlorophyll content, F:(m) and (F:(m)-F:(0))/F:(m) ratio decreased in stressed leaves, while F:(0) increased only in leaves exposed to severe stress (100 and 150 mM). Membrane permeability and lipid peroxidation increased in plants under all stress conditions and in 100 and 150 mM stressed calli, but remained unchanged in 25 mM stressed calli. Salt stress also induced changes relating to antioxidant enzymes: plants under all stress conditions showed a decrease in catalase, peroxidase and SOD activities. Calli under moderate stress (25 mM KCl) showed an increase of catalase, peroxidase and SOD activities, but the activities of peroxidase and SOD decreased when calli were exposed to higher KCl concentrations. The decrease of antioxidant enzyme activities is in tune with lipid peroxidation and membrane permeability increases. On the other hand, calli adapted for 6 months to 100 mM KCl showed an increase of these enzyme activities compared to unstressed calli, while MDA production and membrane permeability were not significantly affected.

Colonization with arbuscular mycorrhizal fungi improves salinity tolerance of tomato (Solanum lycopersicum L.) plants

“…Prevention of lipid peroxidation has been considered as one of the key processes in salinity tolerance of tomato cultivars (Juan et al 2005). Proline, besides its well established role as compatible solute in osmoregulation under stress (Santos et al 2001;Ashraf and Foolad 2007), also plays a significant role in hydroxyl radical scavenging (Alia and Mohanty 1997). Activity of antioxidant defense enzymes was largely induced by AMF in the tomato plants in this work.…”

“…Like other abiotic stresses, salinity also induces oxidative stress in plants (Santos et al 2001;. Plant cells contain an array of protection mechanisms and repair systems that can minimize the occurrence of oxidative damage caused by reactive oxygen species (ROS) (Creissen and Mullineaux 2002).…”

“…A further important role for proline related to enhanced drought and salt tolerance of plants is its ability for scavenging hydroxyl radicals (Rhodes et al 2004). Proline accumulation in mycorrhizal plants subjected to drought has been reported and variable effects of mycorrhizal colonization on proline levels of plants under salt stress have been observed (Santos et al 2001).…”

Environmental stress alters genes expression and induces ovule abortion: reactive oxygen species appear as ovules commit to abort

“…Once ovules were committed to abort, however, the mRNA levels of three other ROS detoxification enzymes decreased. Santos et al (2001) also reported that moderate stress increased catalase, peroxidase, and SOD activities, while higher KCl concentrations decreased peroxidase and SOD activities.…”

Antisense expression of tomato chloroplast omega-3 fatty acid desaturase gene (LeFAD7) enhances the tomato high-temperature tolerance through reductions of trienoic fatty acids and alterations of physiological parameters

“…Membrane permeability was determined by measuring the relative electrolyte conductivity following the method as described previously (Santos et al 2001), with some modifications. Briefly, leaf samples were washed in deionized water to remove surface-adhered ions.…”