Effects of Salt and Water Stress on Plant Growth and on Accumulation of Osmolytes and Antioxidant Compounds in Cherry Tomato

Abstract

The effects of salt and water stress on growth and several stress markers were investigated in cherry tomato plants. Some growth parameters (stem length and number of leaves) and chlorophyll contents were determined every third day during plant growth, and leaf material was collected after 25 and 33 days of treatment. Both stresses inhibited plant growth; chlorophyll levels, however, decreased only in response to high NaCl concentrations. Proline contents largely increased in leaves of stressed plants, reaching levels high enough to play a major role in cellular osmotic adjustment. Despite reports indicating that tomato does not synthesize glycine betaine, the stress-induced accumulation of this osmolyte was detected in cherry tomato, albeit at lower concentration than that of proline. Therefore, it appears that the plants are able to synthesise glycine betaine as a secondary osmolyte under strong stress conditions. Total sugars levels, on the contrary, decreased in stress-treated plants. Both stress treatments caused secondary oxidative stress in the plants, as indicated by a significant increase in malondialdehyde (MDA) contents. Water stress led to an increase in total phenolics and flavonoid contents and a reduction of carotenoid levels in the leaves; flavonoids also increased under high salinity conditions.

Garlic, from Remedy to Stimulant: Evaluation of Antifungal Potential Reveals Diversity in Phytoalexin Allicin Content among Garlic Cultivars; Allicin Containing Aqueous Garlic Extracts Trigger Antioxidants in Cucumber

“…A plausible explanation could be that the overproduction of ROS cause oxidative burst, resulting peroxidation of membrane lipids and alternatively increasing the MDA content (Savicka and Škute, 2010). The increase in MDA content is a reflection of severe stress and our findings are in close agreement with (Hassan et al, 2015) who reported an increased level of MDA content in tomato leaves upon imposition of salt and water stress conditions. Increased MDA content was also reported as a stress condition observed in eggplants during successive cropping conditions (Wang et al, 2015).…”

Towards an Understanding of Physiological and Biochemical Mechanisms of Drought Tolerance in Plant

“…Chlorophyll is one of the major chloroplast components for photosynthesis, and relative chlorophyll content has a positive relationship with photosynthetic rate. The decrease in chlorophyll content under drought stress has been considered a typical symptom of oxidative stress and may be the result of pigment photo-oxidation and chlorophyll degradation as reported in cherry tomato [17].…”

“…Proline is generally considered as a good indicator of environmental stress and there are many reports describing an increase in proline content in response to water stress [17,18]. Ghorbanli et al [18] suggested that Proline is one of the protective molecules that can unite oxygen and free radicals caused by stress.…”

Nitric Oxide as a Signal in Inducing Secondary Metabolites During Plant Stress

“…Some abiotic stress-eliciting responses, including ROS production, lipid peroxidation, the activation of PAL, and osmolyte production, were also mediated by NO. For example, exogenous NO treatment enhanced the production of antioxidation-associated compounds, total phenolic content, proline, and flavonoids in salt-stressed spinach and tomato [111][112][113]. Furthermore, exogenous NO application has also increased the fresh and dry biomasses of edible parts compared to salt alone treated plants.…”