Kinetin and Indole Acetic Acid Promote Antioxidant Defense System and Reduce Oxidative Stress in Maize (Zea mays L.) Plants Grown at Boron Toxicity

Journal of Plant Growth Regulation - A study was conducted to assess the influence of boron (B) toxicity on functioning of antioxidant machinery to counteract oxidative stress in maize (Zea mays...     

Epibrassinolide Application Regulates Some Key Physio-biochemical Attributes As Well As Oxidative Defense System in Maize Plants Grown Under Saline Stress

It was aimed to investigate the ameliorative effect of exogenously applied 24-epibrassinolide (EBR) on some key growth parameters and mineral elements in two salt-stressed maize (PR 32T83 and PR 34N24) cultivars. A factorial experiment was designed with two electrical permeability (EC) levels (1.1 and 8.0 dS/m) and two levels (1.5 and 2.0 µM) of EBR supplied as a seed treatment, foliar spray, or both in combination. The foliar application of EBR was done once a week during the experiment. After 42 days of these treatments, the plants were harvested to assess growth, water relations, and oxidative and antioxidative systems. Salt stress markedly reduced plant fresh and dry weights, maximum fluorescence yield of PS-II, chlorophyll contents, leaf water potential, and leaf K and Ca, but it increased membrane permeability, the activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC. 1.11.1.7), and catalase (CAT; EC. 1.11.1.6) enzymes, and the contents of proline and glycine betaine, leaf sap osmotic pressure, lipid peroxidation, hydrogen peroxide, and leaf Na and Cl. However, both seed treatment and foliar application of EBR to the maize plants exposed to saline conditions enhanced key growth attributes, water relations, and the activities of various antioxidant enzymes as well as the levels of proline, but they reduced electrolyte leakage, and H₂O₂ and MDA contents. Saline stress reduced leaf N, Ca²⁺, K⁺, and P contents as compared to those in the non-stressed plants. Both seed treatment and foliar application of EBR reduced Na⁺ and Cl^? concentrations, but increased those of N, Ca²⁺, K⁺, and P. Foliar application of EBR was more effective in increasing nutrient levels of plants grown at the high saline regime compared to the seed treatment of EBR. The study clearly indicates that both seed treatment and foliar application of EBR at the rate of 2.0 µM can overcome the detrimental effect of salinity stress on maize growth, which was found to be significantly linked to reduced concentrations of Na, Cl, MDA, and H₂O₂ as well as EL and increased activities of key antioxidant enzymes in the maize plants.     

Brassinosteroids Regulate Growth in Plants Under Stressful Environments and Crosstalk with Other Potential Phytohormones

Brassinosteroids (BRs) are an important group of plant steroidal hormones that are actively involved in a myriad of key growth and developmental processes from germination to senescence. Moreover, BRs are known for their effective role in alleviation of stress-induced changes in normal metabolism via the activation of different tolerance mechanisms. Efforts to improve plant growth through exogenous application of BRs (through different modes such as foliar spray, presowing seed treatment, or through root growing medium) have gained considerable ground world over. It has been widely demonstrated that the exogenous application of BRs to stressed plants imparts the stress tolerance mechanisms. In BR-induced regulation of physio-biochemical processes in plants, interaction (crosstalk) of BRs with other phytohormones has been reported. This crosstalk may fine-tune the effective roles of other hormones in regulating stress tolerance. The multifaceted role of BRs consolidated so far has reflected their immense potential to help plants in counteracting the stress-induced changes. The effects of introgression and up- and down-regulation of BR-related genes reported so far to improve crop productivity have been presented here. Strong evidence exists that BRs are involved in signal transduction particularly in the regulation of the mitogen-activated protein kinase (MAPK) cascade, which in turn is involved in controlled development, cell death, and the perception of pathogen-associated molecular pattern (PAMP) signaling. How far BRs are involved in signal transduction pathways operative under stressful environments has also been comprehensively discussed in this review.     

Role of Zinc–Lysine on Growth and Chromium Uptake in Rice Plants under Cr Stress

Journal of Plant Growth Regulation - Chromium (Cr) is a very toxic heavy metal present in agricultural soils. Soils contaminated with Cr are the major source of Cr entrance into the food chain. The...     

Fulvic Acid Prevents Chromium-induced Morphological,Photosynthetic, and Oxidative Alterations in Wheat Irrigated with Tannery Waste Water

Journal of Plant Growth Regulation - Rapid industrialization is potentially contaminating the environment. Tannery is one of the industries producing very high amount of effluents, having a...     

5-Aminolevulinic Acid-Induced Heavy Metal Stress Tolerance and Underlying Mechanisms in Plants

Journal of Plant Growth Regulation - Plants face different types of biotic and abiotic stresses during their life span. Heavy metal (HM) stress is considered as one of the most challenging and...     

Stereoselective uptake and degradation of (±)‐o,p‐DDD pesticide stereomers in water‐sediment system

The environmental stereoselective uptake and degradation of (±)‐o,p‐DDD pesticide stereomers in water‐sediment system are described. The results were analyzed by artificial neural network model. The optimized experimental parameters were concentration of o,p‐DDD streamers (7.0 μg L^?1), experimental time (60 min), pH (6), dose (5.0 g L^?1), and temperature (25°C). The maximum uptake and degradation were 87% and 85% and 33.0% and 30.5% for (?)‐ and (+)‐stereomers of o,p‐DDD in 15‐day time. Both uptake and degraded phenomenon showed first‐order rate reaction. Thermodynamic variables indicated exothermic nature of uptake and degradation processes. The uptake and degradation were slightly higher for (?)‐stereomer than (+)‐stereomer of o,p‐DDD. It was assumed that both uptake and degradation processes are accountable for the removal of the streomers of o,p‐DDD from earth's ecosystem, but the uptake is responsible for major contribution. The magnitudes of relative errors obtained by artificial neural network model were in the range of ±0.2 to 3.5, indicating good applicability of the experimental data. The results are very useful to control the environmental contamination due to the chiral o,p‐DDD pesticide as its two enantiomers have different ecological toxicities.     

Evidence of genetically diverse virulent mating types of <Emphasis Type="Italic">Phytophthora capsici</Emphasis> from <Emphasis Type="Italic">Capsicum annum</Emphasis> L.

Chili pepper (Capsicum annum L.) is an important economic crop that is severely destroyed by the filamentous oomycete Phytophthora capsici. Little is known about this pathogen in key chili pepper farms in Punjab province, Pakistan. We investigated the genetic diversity of P. capsici strains using standard taxonomic and molecular tools, and characterized their colony growth patterns as well as their disease severity on chili pepper plants under the greenhouse conditions. Phylogenetic analysis based on ribosomal DNA (rDNA), β-tubulin and translation elongation factor 1α loci revealed divergent evolution in the population structure of P. capsici isolates. The mean oospore diameter of mating type A1 isolates was greater than that of mating type A2 isolates. We provide first evidence of an uneven distribution of highly virulent mating type A1 and A2 of P. capsici that are insensitive to mefenoxam, pyrimorph, dimethomorph, and azoxystrobin fungicides, and represent a risk factor that could ease outpacing the current P. capsici management strategies.     

Synthesis of aminopyrazole analogs and their evaluation as CDK inhibitors for cancer therapy

We synthesized a library of aminopyrazole analogs to systematically explore the hydrophobic pocket adjacent to the hinge region and the solvent exposed region of cyclin dependent kinases. Structure-activity relationship studies identified an optimal substitution for the hydrophobic pocket and analog 24 as a potent and selective CDK2/5 inhibitor.     

Enhanced biosynthesis of phenazine-1-carboxamide by <Emphasis Type="Italic">Pseudomonas chlororaphis</Emphasis> strains using statistical experimental designs

Phenazine-1-carboxamide (PCN) is one of the major biocontrol agents produced by plant growth-promoting rhizosphere (PGPR) pseudomonads including Pseudomonas chlororaphis. In this study, a combined strategy of genetic modification and statistical experimental designs was applied to obtain mutants of P. chlororaphis strains with high-yield PCN production. To achieve this, the lon gene was knocked out in wild-type P. chlororaphis HT66 and the breeding mutant P3 strain with a non-scar deletion strategy. The resulting HT66Δlon and P3Δlon mutants produced a significantly higher PCN production in shake-flask cultures which was 5- and  9-folds greater than their native counterparts. The potential ability of strain P3Δlon for PCN production was further optimized by statistical designs. A two-level Plackett–Burman (PB) experimental design with six variables was employed to scrutinize medium components that significantly influence PCN production. Notably, glycerol, tryptone, and soy peptone were identified to be the most significant factors (p?<?0.05). Response surface methodology (RSM) based on the central composite design (CCD) was adopted to determine these factors optimal levels and their interactive effects between culture components for PCN production. The predicted maximum PCN production was 9002 mg/L, whereas an actual PCN production of 9174 mg/L was recorded in the validation experiments using the optimal medium containing glycerol 37.08 mL/L, tryptone 20.00 g/L, and soy peptone 25.03 g/L, which was nearly threefolds higher than without optimization and 20-folds higher than the wild-type strain. In conclusion, the results revealed that P. chlororaphis display a high potential for industrial-scale production for phenazine biopesticides.