Abstract
Efficient detoxification of reactive oxygen species (ROS) is thought to play a key role in enhancing the tolerance of plants to abiotic stresses. Although multiple pathways, enzymes, and antioxidants are present in plants, their exact roles during different stress responses remain unclear. Here, we report on the characterization of the different antioxidant mechanisms of tomato plants subjected to heat stress, salinity stress, or a combination of both stresses. All the treatments applied induced an increase of oxidative stress, with the salinity treatment being the most aggressive, resulting in plants with the lowest biomass, and the highest levels of H2O2 accumulation, lipid peroxidation, and protein oxidation. However, the results obtained from the transcript expression study and enzymatic activities related to the ascorbate-glutathione pathway did not fully explain the differences in the oxidative damage observed between salinity and the combination of salinity and heat. An exhaustive metabolomics study revealed the differential accumulation of phenolic compounds depending on the type of abiotic stress applied. An analysis at gene and enzyme levels of the phenylpropanoid metabolism concluded that under conditions where flavonols accumulated to a greater degree as compared to hydroxycinnamic acids, the oxidative damage was lower, highlighting the importance of flavonols as powerful antioxidants, and their role in abiotic stress tolerance.
Highlights
Environmental conditions governing most of the agricultural lands worldwide are often inadequate for crop development and production
Salinity resulted in a downregulation of most of the ascorbate-glutathione cycle enzymes, except for the SOD and APX transcripts which were upregulated, whereas heat led to an upregulation of most of the reactive oxygen species (ROS)-related transcripts measured
Most molecular studies performed on tomato and other horticultural plants of economic interest have been performed via the application of a single stress condition
Summary
Environmental conditions governing most of the agricultural lands worldwide are often inadequate for crop development and production Abiotic stresses such as salinity, high temperature and water scarcity have been reported to cause large economic losses worldwide every year. Our research group has demonstrated that the synthesis and accumulation of some osmoprotectants was altered under the combination of salinity and heat as compared to that observed under the heat or salt stresses applied individually (Rivero et al, 2014) These findings highlight the importance of studying abiotic stress combination for engineering or breeding for plant tolerance to real-world abiotic stress field conditions (Yamaguchi and Blumwald, 2005; Mittler, 2006)
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