Search

• The treatment of EBL and ML alone or in combination significantly increased plant growth, photosynthetic efficiency, and altered various biochemical attributes under combined stress of drought and salt as well as stress-free conditions. • Enhanced levels of antioxidant enzymes and accumulation of proline indicate mitigation of excess ROS elicited by joint application of EBL and ML, which provide tolerance against the combined stress of drought and salt in pea plants. • This study also revealed that co-application of EBL and ML may have great potential for improving crop production under dual stresses of drought and salt and could act as a potent inhibitor of oxidative stress in pea plants. Plant hormones and several small signalling molecules are known to provide tolerance against various abiotic stresses. The individual contributions of 24-Epibrassinolide (EBL) and Melatonin (ML) in enhancing plant tolerance to different abiotic stresses have been well-documented, but their combined effect in alleviating the impact of combined stress remains unexplored. In this study, joint effect of EBL and ML has been tested on growth, photosynthesis, biochemical traits and oxidative stress markers in Pisum sativum (pea) plants exposed to combination of drought and salt stress. The individual application of EBL and ML exhibited nearly similar responses to both stresses. However, when EBL and ML were applied together, significant changes in growth, photosynthetic traits, proline accumulation, and activities of various antioxidant enzymes were observed in pea plants exposed to the combined stress of drought and salt. Enhanced level of antioxidant enzymes and accumulation of proline indicates mitigation of excess ROS elicited by joint application of EBL and ML that provides tolerance against combined stress of drought and salt in pea plants. This study indicates that joint application EBL and ML is an operational approach for mitigation of combined stress of drought and salt in plants and could be exploited for sustainable agricultural practices on the stressed soils. [ABSTRACT FROM AUTHOR]

Sugars are the most important regulators that facilitate many physiological processes, such as photosynthesis, seed germination, flowering, senescence, and many more under various abiotic stresses. Exogenous application of sugars in low concentration promote seed germination, up regulates photosynthesis, promotes flowering, delayed senescence under various unfavorable environmental conditions. However, high concentration of sugars reverses all these physiological process in a concentration dependent manner. Thus, this review focuses the correlation between sugars and their protective functions in several physiological processes against various abiotic stresses. Keeping in mind the multifaceted role of sugars, an attempt has been made to cover the role of sugar-regulated genes associated with photosynthesis, seed germination and senescence. The concentration of sugars determines the expression of these sugar-regulated genes. This review also enlightens the interaction of sugars with several phytohormones, such as abscisic acid, ethylene, cytokinins and gibberellins and its effect on their biosynthesis under abiotic stress conditions. [ABSTRACT FROM AUTHOR]

The present investigation was conducted to evaluate the silicon (Si) mediated responses in different cultivars of Indian mustard (Brassica juncea) and to evaluate if Si could be used as an essential, beneficial, or quasi-essential element for growth and development of these cultivars. Surface sterilized seeds were sown in pots and allowed to germinate under natural environmental conditions. At 10, 12, 14, 16, and 18 days after germination, a range of Si concentrations (0.0, 0.2, 0.4, 0.8 and 1.6 mM) was administered to the soil and at 30 days post germination the plants were sampled to assess growth and development, leaf gas exchange traits and plant biochemical parameters, including activities of carbonic anhydrase, catalase, peroxidase, superoxide dismutase, and protein and proline content. The results demonstrate a dual response to Si concentration: 0.8 mM of Si significantly increased plant growth and development (length of root and shoot, fresh and dry biomass, and leaf area) and photosynthetic efficiency, and enhanced the antioxidant response in T-59 over all the other cultivars tested, whereas, 1.6 mM of Si significantly reduced the above parameters. It is therefore concluded that low levels of Si could be used as a quasi-essential element for enhanced photosynthetic efficiency and antioxidant response ofBrassica junceaplants; however, the response is cultivar specific and concentration dependent. [ABSTRACT FROM PUBLISHER]

24-Epibrassinolide (EBL) and Selenium (Se) individually confer tolerance to various abiotic stresses, but their interactive effect in the regulation of copper (Cu) homeostasis in plants exposed to toxic levels of Cu is poorly investigated. This study provides an insight into the effects of EBL (foliar) and/or Se (through sand) on Brassica juncea plants exposed to toxic levels of Cu. The combined effect of EBL and Se on compartmentalization of Cu, oxidative stress markers, photosynthetic machinery and biochemical traits in B. juncea were analyzed. Application of EBL and Se through different mode modulated the compartmentalization of Cu in different parts of plants, enhanced the photosynthetic traits, and activities of various antioxidant enzymes and proline accumulation in B. juncea under excess copper levels. These enhanced levels of antioxidant enzymes, proline (osmolyte) accumulation triggered by combination of EBL and Se could have conferred tolerance to the B. juncea plants under toxic level of copper and also maintained Cu homeostasis in various parts of plants. This study indicates that combination of EBL and Se through different mode is an operative approach for Cu detoxification in plants and could be exploited for removal of excess copper from polluted soil. [ABSTRACT FROM AUTHOR]

This study was conducted to provide an insight into the effect of Se (through soil) induced changes in Brassica juncea plants in the presence and absence of 24-epibrassinolide (EBL; foliar). The Se treatments showed dual response, 10 μM of Se significantly increased growth, water relations, photosynthetic attributes along with carbonic anhydrase activity whereas its higher concentrations proved inhibitory in concentration dependent manner. The follow-up application of EBL to the Se stressed plants improved growth, water relations, photosynthesis and simultaneously enhanced the various antioxidant enzymes viz. catalase, peroxidase and superoxide dismutase with the excess accumulation of proline. In addition to this, 10 μM Se increases the efficacy of 10 −8 M of EBL and both in combination showed maximum increase for the growth and photosynthetic traits of plants. On the other hand, the elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the Se-stressed plants resulting in improved growth, water relations and photosynthesis. [ABSTRACT FROM AUTHOR]

Low temperature can delay growth and development, reduce productivity, or cause plant death. An experiment was carried out to determine the most sensitive and most tolerant tomato (Solanum lycopersicumL.; variety S-22, Selection N-5, Pusa Gorav, K-21, Pusa Ruby, Hera Research, and PKM-1) to low temperature. Forty-day-old seedlings were exposed to day/night temperatures of 10/3°C, 12/7°C, 20/14°C, or 25/18°C (control) for 24 h in a plant growth chamber and then transferred to ambient environmental conditions in a net house and maintained for 60 days. Decreasing temperature led to decreases in growth, chlorophyll content, and photosynthesis rate in all varieties. Activity of antioxidant enzymes catalase, peroxidase, and superoxide dismutase and proline accumulation in leaves increased in all varieties as temperature decreased. Variety S-22 had the most antioxidant enzyme activity and proline accumulation and ‘PKM-1’ had the lowest antioxidant enzyme activity and proline content; these were classified as tolerant and sensitive, respectively. Tolerant tomato varieties provide options for producers where low temperature can interfere with plant development. [ABSTRACT FROM PUBLISHER]

Hydrogen peroxide (H2O2) in minute concentrations serves as a signaling molecule for processes involved in the growth and development of plants. The present study aimed to explore the role of seed treatment with H2O2on growth biomarkers, photosynthetic traits, activities of carbonic anhydrase, and various antioxidant enzymes in 45-day-old plants of mung bean (Vigna radiataL. Wilczek) cv. SML-668 under non-stress conditions. The seeds were soaked in 0, 0.01, 0.1, or 0.5 mM H2O2for 2, 4, or 8 h, and then inoculated withRhizobium, sown in sandy loam soil, and allowed to grow for 45 days. The plants that developed from the H2O2-treated seeds demonstrated improved growth and photosynthetic attributes, enhanced activity of various antioxidant enzymes (e.g., catalase, peroxidase, and superoxide dismutase), and higher accumulation of proline than plants from non-treated seeds. The H2O2-triggered upregulation of antioxidant enzymes and proline (osmolyte) could have resulted in the observed improvement of growth and development. Out of the three concentrations of H2O2tested, seed soaking with 0.1 mM for 4 h proved to be the best. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish relationship between manganese-induced toxicity and antioxidant system response in Brassica juncea plants and also to investigate whether brassinosteroids activate antioxidant system to confer tolerance to the plants affected with manganese induced oxidative stress. Brassica juncea plants were administered with 3, 6, or 9 mM manganese at 10-day stage for 3 days. At 31-day stage, the seedlings were sprayed with deionized water (control) or 10 M of 24-epibrassinolide, and plants were harvested at 45-day stage to assess growth, leaf gas-exchange traits, and biochemical parameters. The manganese treatments diminished growth along with photosynthetic attributes and carbonic anhydrase activity in the concentration-dependent manner, whereas it enhanced lipid peroxidation, electrolyte leakage, accumulation of HO as well as proline, and various antioxidant enzymes in the leaves of Brassica juncea which were more pronounced at higher concentrations of manganese. However, the follow-up application of 24-epibrassinolide to the manganese stressed plants improved growth, water relations, and photosynthesis and further enhanced the various antioxidant enzymes viz. catalase, peroxidase, and superoxide dismutase and content of proline. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the manganese-stressed plants resulting in improved growth and photosynthetic attributes. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to establish relationship between boron induced oxidative stress and antioxidant system in Vigna radiata plants and also to investigate whether brassinosteroids will enhance the level of antioxidant system that could confer tolerance to the plants from the boron induced oxidative stress. The mung bean (V. radiata cv. T-44) plants were administered with 0.50, 1.0 and 2.0mM boron at 6d stage for 7d along with nutrient solution. At 13d stage, the seedlings were sprayed with deionized water (control) or 10−8 M of 28-homobrassinolide and plants were harvested at 21d stage to assess growth, leaf gas-exchange traits and biochemical parameters. The boron treatments diminished growth, water relations and photosynthetic attributes along with nitrate reductase and carbonic anhydrase activity in the concentration dependent manner whereas, it enhanced lipid peroxidation, electrolyte leakage, accumulation of H2O2 as well as proline, and various antioxidant enzymes in the leaves of mung bean which were more pronounced at higher concentrations of boron. However, the follow-up application of 28-homobrassinolide to the boron stressed plants improved growth, water relations and photosynthesis and further enhanced the various antioxidant enzymes viz. catalase, peroxidase and superoxide dismutase and content of proline. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the B-stressed plants resulting in improved growth, water relations and photosynthetic attributes. [Copyright &y& Elsevier]

Seeds of five wheat ( Triticum aestivum) cultivars (PBW-373, UP-2338, DL-LOK-01, DL-373, and HD-2338) were sown in earthen pots and 10-day-old seedlings were exposed to 0, 50, and 100 μM of nickel (Ni) in the form of nickel chloride. At the 20-day stage, seedlings were sprayed with 0.01 μM of 28-homobrassinolide (HBL). The results of the experiment at the 30-day stage revealed a decline in the dry mass per plant, leaf area, leaf water potential, and net photosynthetic rate with concomitant decline in the activities of various enzymes (viz . carbonic anhydrase and nitrate reductase) with an increasing concentration of Ni. However, an increase in proline content and the activities of catalase, peroxidase, and superoxide dismutase was observed as a result of an increase in Ni concentration. Moreover, the treatment of these stressed plants with HBL enhanced the activities of carbonic anhydrase and nitrate reductase, catalase, peroxidase, and superoxide dismutase. The proline content in the leaves also increased, which is known to act as an osmolyte and reactive oxygen species scavenger. The toxic effects generated by Ni were ameliorated by HBL through an improved antioxidant system and osmolyte. Moreover, improvement of photosynthetic parameters and growth characteristics further strengthen our belief that HBL acted as a potent stress alleviator. [ABSTRACT FROM AUTHOR]

Seeds of Indian mustard ( Brassica juncea (L.) Czern. et Coss.) were exposed to 0, 50, 100 and 150 mmol/L NaCl for 8 h and seeds were sown in an earthen pot. These stressed seedlings were subsequently sprayed with 10 μmol/L salicylic acid (SA) at 30 d and were sampled at 60 d to assess the changes in growth, photosynthesis and antioxidant enzymes. The seedlings raised from the seeds treated with NaCl had significantly reduced growth and the activities of carbonic anhydrase, nitrate reductase and photosynthesis, and the decrease was proportional to the increase in NaCl concentration. However, the antioxidant enzymes (catalase, peroxidase and superoxide dismutase) and proline content was enhanced in response to NaCl and/or SA treatment, where their interaction had an additive effect. Moreover, the toxic effects generated by the lower concentration of NaCl (50 mmol/L) were completely overcome by the application of SA. It was, therefore, concluded that SA ameliorated the stress generated by NaCl through the alleviated antioxidant system. [ABSTRACT FROM AUTHOR]

Glucose is recognized as signaling molecule that regulates growth and development of plants under various environmental cues, but their effect in regulation of copper induced toxicity in plants is not yet investigated. This study revealed the effect of exogenously sourced glucose on Cucumber plants exposed to increasing concentration of copper. Glucose mediated response on growth performance, photosynthetic efficiency, antioxidant enzymes, oxidative stress markers, ion uptake were analyzed in the presence and absence of copper. Glucose alone and in combination with lower concentration of copper improved the growth, photosynthetic performance, and antioxidant capacity of cucumber plants. However, higher concentrations of copper alone showed oxidative damage through increased electrolyte leakage, H 2 O 2 accumulation, lipid peroxidation and reduced uptake of macronutrients. Application of glucose to copper-stressed plants enhanced activities of Rubisco, antioxidant enzymes, proline accumulation and maintained copper level in aerial parts of plants. These enhanced activities of antioxidant enzymes, proline accumulation, uptake of NPK and maintained equilibrium of copper in plants, leading to detoxification of copper stress in cucumber plants. This study provides an understanding that exogenous application of glucose can be employed as vital biochemical approach in alleviating copper-induced toxicity and could be utilized as phytoremediation technique for removal of excess transition metal from polluted soil. [Display omitted] • Lower concentration of Cu improved growth and photosynthetic efficiency whereas, higher concentration induced toxicity. • Cu toxicity imbalances the ROS and antioxidant system with increased lipid peroxidation, and H 2 O 2 content. • Glucose act as signaling molecule that improved growth, water relation and photosynthetic efficiency. • Glucose treatment to the Cu-stressed plants recovered the damage through enhanced antioxidant system. [ABSTRACT FROM AUTHOR]

This study was designed to assess the combined effect of both aluminium and salt stress on the processes and molecules pertinent to these stresses and to establish relationship between these two stresses on the basis of photosynthetic attributes and antioxidant enzymes in wheat cultivars. Seven different varieties of wheat grown under environmentally controlled conditions. At 10 days stage of growth, plants were treated with NaCl (100 or 150 mM) and/or Al (05 or 10 mM) through soil. At 30 days stage, treatment of Al and salt stress alone showed the similar deteriorating response in terms of photosynthetic traits and LWP whereas, electrolyte leakage, lipid peroxidation, H2O2content along with enzymes of antioxidant and proline content varied in different varieties of wheat. Moreover, the combination of Al and salt stress further increased the antioxidant enzymes and proline accumulation. However, salt stress restrict the uptake of Al by roots in significant manner under combine treatment of Al and salt stress. The pattern of tolerance was observed on the basis of enhanced antioxidant system and proline accumulation and cultivar LOK-1 and 502 showed maximum and minimum tolerance respectively against the combination of salt and aluminium stress. [ABSTRACT FROM AUTHOR]

Abstract: The plants of Vigna radiata c.v. T-44 were supplemented with 28-homobrassinolide (HBL) both in the presence or absence of high temperature and/or NaCl and were sampled, 18 days after sowing (DAS). The plants exposed to high temperature and/or NaCl exhibited a significant decline in growth, photosynthetic parameters and a maximum quantum yield of PSII. However, the follow up treatment with HBL detoxified the stress generated by high temperature and/or NaCl and significantly improved the values for the above parameters. The high temperature and/or NaCl increased electrolyte leakage and lipid peroxidation, and decreased the membrane stability index (MSI) and leaf water potential (ψ). However, HBL treatment, in the absence of stress, improved the MSI and leaf water potential (ψ) but could not influence electrolyte leakage and lipid peroxidation. The antioxidative enzymes and the level of proline exhibited a significant increase in the response to HBL as well as to high temperature and/or NaCl stress. [Copyright &y& Elsevier]