Benzylaminopurine and abscisic acid mitigates cadmium and copper toxicity by boosting plant growth, antioxidant capacity, reducing metal accumulation and translocation in bamboo ['Pleioblastus pygmaeus' (Miq.)] plants

An in vitro experiment was conducted to determine the influence of phytohormones on the enhancement of bamboo resistance to heavy metal exposure (Cd and Cu). To this end, one-year-old bamboo plants (Pleioblastus pygmaeus (Miq.) Nakai.) contaminated by 100 µM Cd and 100 µM Cu both individually and in combination were treated with 10 µM, 6-benzylaminopurine and 10 µM abscisic acid. The results revealed that while 100 µM Cd and 100 µM Cu accelerated plant cell death and decreased plant growth and development, 10 µM 6-benzylaminopurine and 10 µM abscisic acid, both individually and in combination, increased plant growth by boosting antioxidant activities, non-antioxidants indices, tyrosine ammonia-lyase activity (TAL), as well as phenylalanine ammonia-lyase activity (PAL). Moreover, this combination enhanced protein thiol, total thiol, non-protein, glycine betaine (GB), the content of proline (Pro), glutathione (GSH), photosynthetic pigments (Chlorophyll and Carotenoids), fluorescence parameters, dry weight in shoot and root, as well as length of the shoot. It was then concluded that 6-benzyl amino purine and abscisic acid, both individually and in combination, enhanced plant tolerance under Cd and Cu through several key mechanisms, including increased antioxidant activity, improved photosynthesis properties, and decreased metals accumulation and metal translocation from root to shoot

Effect of 28-homobrassinolide on the performance of sensitive and resistant varieties of Vigna radiata

A study was undertaken to examine the morpho-physiological alterations under different concentrations of 28-homobrassinolide (HBL) in two contrasting varieties of Vigna radiata. Sterilized seeds of V. radiata (T-44 and PDM-139) were inoculated with specific Rhizobium and allowed to grow and then 14 day old seedlings were exposed to different concentrations (0, 10−10, 10−8, or 10−6 M) of HBL and allowed to grow under natural environmental conditions. At the 15 and 21 day stage, plants were harvested to evaluate various parameters. Results clearly indicated that growth bio-markers, accumulation of proline and activities of various antioxidant enzymes increased significantly in T-44 at a later stage of growth in the presence of HBL whereas, 10−8 M showed the most promising response. It is concluded that HBL modifies the physiological functions and biochemical metabolism of V. radiata by increasing photosynthetic efficiency at an early stage of growth and antioxidant system in T-44 at a later stage of plant growth that are manifested in growth at later stages. It is believed that increased accumulation of proline and enhanced antioxidant system provide strength to the plants to withstand environmental cues. Keywords: Antioxidant system, Chlorophyll, Morpho-physiological response, Photosynthetic efficiency, Prolin

Effect of Anthropogenic Activities on Accumulation of Heavy Metals in Legumes Crops, Riyadh, Saudi Arabia

AbstractThe objective was to look at the effect of anthropogenic activities on the accumulation of heavy metals; in four legumes crop plants. Pisum sativum L., Vicia faba L., Glycine max and Vigna sinensis, during summer and winter plants exposed to five levels of ambient air pollution by quantifying heavy metals (Cu, Mn, Pb and Zn) concentrations in the leaves, pods and grains. Results indicated that air pollution significantly increased the heavy metal concentrations in the leaves, pods and grains. Toxic concentrations were found in the plants grown at L3, L4 and L5

Traffic and industrial activities around Riyadh cause the accumulation of heavy metals in legumes: A case study

AbstractThe objective of this study was to analyse the effect of the continuously increasing anthropogenic activities around Riyadh, Saudi Arabia on the accumulation of heavy metals in leguminous crops. This study determined whether four legume crops, Pisum sativum L., Vicia faba L., Glycine max and Vigna sinensis, could accumulate the heavy metals Cu, Mn, Pb and Zn in their leaves, pods and grains during the summer when grown under conditions with ambient air pollution from heavy traffic and industrial activities in Riyadh, Saudi Arabia. The effect of the air pollution was examined by quantifying the protein and trace element Cu, Mn, Pb and Zn concentrations in the leaves, pods and grains of the four plant species. Analysis of the results indicated that air pollution significantly increased the heavy metal concentrations in the leaves, pods and grains. Toxic concentrations of the heavy metals were found in the plants grown at L3, L4 and L5. In conclusion, the air pollution increases as the traffic, industrial activities and population density increase

Exogenously-Sourced Salicylic Acid Imparts Resilience towards Arsenic Stress by Modulating Photosynthesis, Antioxidant Potential and Arsenic Sequestration in <i>Brassica napus</i> Plants

In the current study, salicylic acid (SA) assesses the physiological and biochemical responses in overcoming the potential deleterious impacts of arsenic (As) on Brassica napus cultivar Neelam. The toxicity caused by As significantly reduced the observed growth and photosynthetic attributes and accelerated the reactive oxygen species (ROS). Plants subjected to As stress revealed a significant (p ≤ 0.05) reduction in the plant growth and photosynthetic parameters, which accounts for decreased carbon (C) and sulfur (S) assimilation. Foliar spray of SA lowered the oxidative burden in terms of hydrogen peroxide (H2O2), superoxide anion (O2•−), and lipid peroxidation in As-affected plants. Application of SA in two levels (250 and 500 mM) protected the Brassica napus cultivar from As stress by enhancing the antioxidant capacity of the plant by lowering oxidative stress. Among the two doses, 500 mM SA was most effective in mitigating the adverse effects of As on the Brassica napus cultivar. It was found that SA application to the Brassica napus cultivar alleviated the stress by lowering the accumulation of As in roots and leaves due to the participation of metal chelators like phytochelatins, enhancing the S-assimilatory pathway, carbohydrate metabolism, higher cell viability in roots, activity of ribulose 1, 5-bisphosphate carboxylase (Rubisco), and proline metabolism through the active participation of γ-glutamyl kinase (GK) and proline oxidase (PROX) enzyme. The current study shows that SA has the capability to enhance the growth and productivity of B. napus plants cultivated in agricultural soil polluted with As and perhaps other heavy metals

Foliar application of 28-homobrassinolide mitigates salinity stress by increasing the efficiency of photosynthesis in Brassica juncea

Prior to sowing, seeds of Brassica juncea Czern and Coss cv. Varuna were soaked in water (controls) or in 50, 100 or 150 mM of sodium chloride (NaCl) for 6 h. The resulting plants, at 15, 30 and 45 days after sowing (DAS) were either not treated (controls) or were treated with aqueous solutions of the hormone 28-homobrassinolide (HBL), which was applied to their foliage in concentrations of 10-10, 10-8 or 10-6 M. The concentration of NaCl showed an inverse correlation with the activity of nitrate reductase (EC 1.6.6.1), the activity of carbonic anhydrase (EC 4.2.1.1), chlorophyll content at 60 DAS, the rate of photosynthesis at 60 DAS, and seed yield at 140 DAS (at harvest), all of which decreased in parallel with increases in NaCl concentration. However, treatment with HBL attenuated those decreases and neutralized the ill effects of salinity stress, completely at the lowest NaCl concentration and partially at the higher NaCl concentrations. The seed yield of the crop can be increased by the foliar application of HBL, even under conditions of salinity stress

SALICYLIC ACIDPlant Growth and Development /

XVI, 389 p. 63 illus., 9 illus. in color.online r

5-Aminolevulinic Acid Induces Chromium [Cr(VI)] Tolerance in Tomatoes by Alleviating Oxidative Damage and Protecting Photosystem II: A Mechanistic Approach

Chromium [Cr(VI)] pollution is a major environmental risk, reducing crop yields. 5-Aminolevunic acid (5-ALA) considerably improves plant abiotic stress tolerance by inducing hydrogen peroxide (H2O2) and nitric oxide (NO) signalling. Our investigation aimed to uncover the mechanism of tomato tolerance to Cr(VI) toxicity through the foliar application of 5-ALA for three days, fifteen days before Cr treatment. Chromium alone decreased plant biomass and photosynthetic pigments, but increased oxidative stress markers, i.e., H2O2 and lipid peroxidation (as MDA equivalent). Electrolyte leakage (EL), NO, nitrate reductase (NR), phytochelatins (PCs), glutathione (GSH), and enzymatic and non-enzymatic antioxidants were also increased. Foliar application of 5-ALA before Cr treatment improved plant growth and photosynthetic pigments, diminished H2O2, MDA content, and EL, and resulted in additional enhancements of enzymatic and non-enzymatic antioxidants, NR activity, and NO synthesis. In Cr-treated tomato seedlings, 5-ALA enhanced GSH and PCs, which modulated Cr sequestration to make it nontoxic. 5-ALA-induced Cr tolerance was further enhanced by sodium nitroprusside (SNP), a NO donor. When sodium tungstate (ST), a NR inhibitor, was supplied together with 5-ALA to Cr-treated plants, it eliminated the beneficial effects of 5-ALA by decreasing NR activity and NO synthesis, while the addition of SNP inverted the adverse effects of ST. We conclude that the mechanism by which 5-ALA induced Cr tolerance in tomato seedlings is mediated by NR-generated NO. Thus, NR and NO are twin players, reducing Cr toxicity in tomato plants via antioxidant signalling cascades

Mitigation of sodium chloride toxicity in Solanum lycopersicum L. by supplementation of jasmonic acid and nitric oxide

We investigated the effects of exogenous application of jasmonic acid (JA) and nitric oxide (NO) on growth, antioxidant metabolism, physio-biochemical attributes and metabolite accumulation, in tomato (Solanum lycopersicum L.) plants exposed to salt stress. Treating the plants with NaCl (200 mM) resulted in considerable growth inhibition in terms of biomass, relative water content, and chlorophyll content, all of which were significantly improved upon application of JA and NO under both normal and NaCl-stress treatments. Salt treatment particularly 200 mM NaCl caused an apparent increase in electrolyte leakage, lipid peroxidation, and hydrogen peroxide production, which were reduced by exogenous application of JA and NO. Salt treatment triggered the induction of antioxidant system by enhancing the activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). Application of JA and NO separately as well as in combination caused a significant improvement in activities of SOD, CAT, APX, and GR activities. JA and NO either applied individually or in combination boosted the flavonoid, proline and glycine betaine synthesis under NaCl treatments. In conclusion, the exogenous application of JA and NO protected tomato plants from NaCl-induced damage by up-regulating the antioxidant metabolism, osmolyte synthesis, and metabolite accumulation