Induction of phytochelatins and flavonoids in cadmium polluted Berberis thunbergii

Cadmium tolerance has been widely studied in various plant species. The study was undertaken to assess the response of Berberis thunbergii, commonly growing under urban conditions, to increasing concentrations of cadmium (1, 4 and 16 mg of Cd kg–1 soil). Experiments were conducted from June to August in a greenhouse. Accumulation of cadmium ions in barberry leaves was observed, at a simultaneous occurrence of mechanisms reducing its harmful effects by an increased synthesis of phytochelatins (PCs). Generation of PCs – putative heavy metal chelators was related to the phytochelatin synthase activity (PCS) and the level of metal accumulation. Increased contents of anthocyanins and flavonols in cadmium polluted barberry, considering that it is a coloured-leaf plant seems important in aspect of their multifunctional role in plant-environment interactions. Besides the capacity to chelate heavy metals, flavonoids are antioxidants and efficiently scavenge free radicals. Moreover, the content of chloroplast pigments was determined, but the changes were non-significant

Spermidine Modify Antioxidant Activity in Cucumber Exposed to Salinity Stress

The effects of short-term 48 h long NaCl-stress and spermidine level modification on polyamines level and antioxidant status in cucumber (Cucumis sativus cv. Dar) leaves were investigated. Seedlings kept in nutrient solutions treated with 50 mM NaCl for 48 h exhibited reduced relative water content and accumulation of free polyamines, especially spermidine. Salinity stress caused an increase in superoxide radicals and hydrogen peroxide generation during the salinity-induced increase in antioxidant enzyme activities. Spermidine application before stress resulted in a marked increase in spermidine and spermine contents in the leaves of salt-stressed cucumber seedlings. Additionally, increased spermidine/spermine level mobilised the antioxidant enzyme’s activity and limited reactive oxygen species content. Polyamine synthesis inhibitor (MGBG) slightly decreased spermidine and spermine levels during salinity and reversed the antioxidant activity mobilisation. These results showed that Spd modifications significantly improved PAs, enhancing salinity stress tolerance by detoxifying ROS. Our findings determined the implication of PAs for improving the salinity tolerance of important vegetable species

Enhancing Lettuce Drought Tolerance: The Role of Organic Acids in Photosynthesis and Oxidative Defense

The aim of this study was to investigate the effects of maleic acid (MA), salicylic acid (SA), and citric acid (CA) on alleviating the drought stress of a lettuce (Lactuca sativa L.) hydroponic culture. The effect of these organic acids was tested under stress conditions induced by polyethene glycol (PEG 6000) at 5% and 7.5% concentrations. Drought stress reduced the fresh and dry matter yields of plants. The acid treatment caused increasing tendencies in the fresh weight yield:control (SA, MA), PEG 7.5% (SA, MA, CA)) and dry weight yield (control (SA, MA), PEG 5% (MA), PEG 7.5% (SA, MA)). The acid treatment also enhanced the nutrient uptake of stressed plants: SA: N (PEG 7.5%), K (PEG 5 and 7.5%); MA: N, P, K, Ca (PEG 5 and 7.5%). This work found that chlorophyll a and b amounts did not change under applied experimental conditions. Most parameters of chlorophyll fluorescence did not depend on either the level of applied water stress (PEG level) or the type of spraying. Drought stress increased leaf superoxide anion (O2•−) and malondialdehyde (MDA) levels but decreased H2O2. Proline (Pro) and phenolic compounds (TFC), including flavonols (Fla), accumulated more in stressed plants. Drought stress also affected the chlorophyll fluorescence. Our results suggest that acids can improve plant tolerance to drought stress by boosting the antioxidant defence system and reducing the oxidative damage caused by reactive oxygen species