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The present study was conducted to assess the effectiveness of exogenously applied l-Methionine (Met) in drought stress tolerance of two broccoli (Brassica oleracea L. var. italica) cultivars. Fifty-day-old seedlings of two broccoli cultivars were exposed to control [100% field capacity (F.C.)] and water deficit stress (60% F.C.). After 30 days of imposition of drought stress, broccoli plants were subjected to varying (15 and 30 mg/L) concentrations of Met along with a control as a foliar spray. Water deficit stress caused a significant reduction in plant growth and yield attributes of both broccoli cultivars. Drought stress also negatively affected the leaf and head characteristics of broccoli such as head weight and chlorophyll pigments of both cultivars, while the levels of ascorbic acid (AsA), glycinebetaine (GB), total phenolics, proline contents as well the activities of key enzymes including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly enhanced in both leaf and head of broccoli. Foliar applied Met prominently improved the leaf and head chlorophyll pigments, GB, AsA, total phenolic contents and activities of SOD, POD, and CAT enzymes in both cultivars of broccoli under stress as well as non-stress conditions. Overall, the results revealed that foliar applied Met was effective in upregulating the growth, yield and leaf and head oxidative defense system of broccoli, and thus suggested the active involvement of Met in improving the growth and yield potential of both broccoli cultivars under stress and non-stress conditions. [ABSTRACT FROM AUTHOR]

Fullerenols are carbon nanoparticles that have been declared as free radical sponges. There is a need to take a prudent path toward its applications in various biological systems. For plants, polyhydroxy fullerenes can be beneficial nanozymes with the ability to scavenge all forms of reactive oxygen species produced within sub-cellular compartments. However, limited information is available regarding the role of these synthetic nano-antioxidants within plant biosystems. The unique chemistry of fullerenes makes them behave as nanozymes that can neutralize all reactive oxygen and nitrogen forms. This property can be utilized for oxidative stress tolerance among plants under stressful environments. Therefore, the knowledge of plant–fullerenol interactions is crucial. The present review describes molecular mechanisms regarding its effects at sub-cellular, cellular, and tissue levels of organization. In addition, the effects of various fullerenol derivatives on different plant species are also provided at length in this review to give insights regarding fullerenol-induced regulation of plant growth and crop protection. [ABSTRACT FROM AUTHOR]

Plant biofibers are of great economic and commercial importance. Among various fiber producing crops, cotton (Gossypium hirsutum L.), hemp (Cannabis sativa L.), flax (Linum usitatissimum L.), kenaf (Hibiscus cannabinus L.), and jute (Corchorus capsularis L.) are of prime importance. Fibers harvested from these crops are of fine quality and have a significant commercial value worldwide. Owing to multiple structural and functional roles of these fibers within plants, the mechanical properties vary to a considerable extent. In the present review, insights into the history, geographical distribution, and production of these crops on saline soils is discussed. The salinity stress tolerance of the fiber crops can be improved via improvement in free radical scavenging, upregulation of antioxidants, potassium retention, enhanced osmolyte synthesis, and accumulation and better ion partitioning. Biotechnological approaches to increase tolerance and fiber quality under salt-affected areas include development of transgenic fiber crops for Na+ vacuolar sequestration and improvements in physio-biochemical attributes. [ABSTRACT FROM AUTHOR]

Soil amendments are known to promote several plant growth parameters. In many agro-ecosystems, water scarcity and drought induced phosphorus deficiency limits crop yield significantly. Considering the climate change scenario, drought and related stress factors will be even more severe endangering the global food security. Therefore, two parallel field trials were conducted to examine at what extent soil amendment of leonardite and humic acid would affect drought and phosphorus tolerance of maize. The treatments were: control (C: 100% A pan and 125 kg P ha−1), P deficiency (phosphorus stress (PS): 62.5 kg P ha−1), water deficit stress (water stress (WS): 67% A pan), and PS + WS (67% A pan and 62.5 kg P ha−1). Three organic amendments were (i) no amendment, (ii) 625 kg S + 750 kg leonardite ha−1 and (iii) 1250 kg S + 37.5 kg humic acid ha−1) tested on stress treatments. Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, Fv/Fm, RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H2O2 in maize plants. The combined stress of drought and P deficiency decreased further related plant traits. Humic acid and leonardite enhanced leaf P and yield in maize plants under PS. A significant increase in related parameters was observed with humic acid and leonardite under WS. The largest increase in yield and plant traits in relation to humic acid and leonardite application was observed under combined stress situation. The use of sulfur-enriched amendments can be used effectively to maintain yield of maize crop in water limited calcareous soils. [ABSTRACT FROM AUTHOR]

In this study, the Sr22 gene was isolated and prepared for transformation in disease-susceptible commercial high-yielding wheat (Triticum aestivum L.) cultivar Lasani-2008. The Sr22 fragment was initially inserted in plasmid pUC57 for sequence confirmation before performing further experiments. After confirmation, Sr22 was subcloned in pGreen0029 which helped in further cloning and ligation. pUC57-Sr22 was restricted with Nru1 and BamH1, while pGreen0029 was restricted with EcoRV and BamH1 and ligated. From pGreen0029, Sr22 was eluted and ligated in pJIT163 to insert the 2 × 35S promoter and CaMV terminator using Xho1 and BamH1 and Sal1. At this stage, the expression cassette was completed. The 2 × 35Sp-Sr22-CaMVt was then ligated in pGreen0029 and transferred to Agrobacterium along with pSOUP. pSOUP helped pGreen0029 to insert 2X35Sp-Sr22-CaMVt in the callus of Lasani-2008, along with kanamycin-resistant gene. Transgenic callus was used for regeneration of the whole plant by tissue culture. Transgenic plants were further tested by PCR, qPCR and SDS-PAGE. The transgenic Lasani-2008 showed substantial resistance against stem rust in both seedling and adult plant stages. The results also showed that transgenic Lasani-2008 has increased average yield of grains (i.e., 4893 ± 148 kg/ha) as compared to non-transgenic Lasani-2008 (i.e., with average yield of gains 4762 ± 103 kg/ha). Sr22 containing lines and the transgenic developed in this study can be used in breeding systems. Transgenic seeds developed will be shared with breeding institutes and breeders should use this information to develop new varieties. [ABSTRACT FROM AUTHOR]

Alpha-tocopherol (α-Toc) is a member of the vitamin E family and is lipid soluble. Its biosynthesis is by the reaction of isopentyl diphosphate and homogentisic acid in plastid membranes. The putative biochemical activities of tocopherols are linked with the formation of tocopherol quinone species, which subsequently undergo degradation and recycling within cells/tissues. α-Toc plays a key role in a variety of plant metabolic processes throughout the ontogeny of plants. It can maintain the integrity and fluidity of photosynthesizing membranes. It can also neutralize lipid peroxy radicals, consequently blocking lipid peroxidation by quenching oxidative cations. It preserves membrane integrity by retaining membranous structural components under environmental constraints such as water deficiency, high salt content, toxic metals, high/low temperatures, and radiations. α-Toc also induces cellular signalling pathways within biological membranes. Its biosynthesis varies during growth and developmental stages as well as under different environmental conditions. The current review primarily focuses on how α-Toc can regulate various metabolic processes involved in promoting plant growth and development under stress and non-stress and how it can effectively counteract the stress-induced high accumulation of reactive oxygen species (ROS). Currently, exogenous application of α-Toc has been widely reported as a potential means of promoting resistance in plants to a variety of stressful environments. [ABSTRACT FROM AUTHOR]

Two independent experiments were performed to assess the role of thiourea (TU)-mediated nitric oxide (NO) in mitigating boron toxicity (BT) in bread wheat (Triticum aestivum L. cv. Pandas) and durum wheat (Triticum durum cv. Altıntoprak 98) plants. In the first experiment, plants of the two wheat species were grown under control (0.05 mM B) and BT (0.2 mM B) supplied to nutrient solution for 4 weeks after germination. These two treatments were also combined with TU spray at 200 or 400 mg L−1 once a week during the period of stress. Boron toxicity reduced dry weights of shoot and root, leaf total chlorophyll, efficiency of photosystem II (Fv/Fm) and leaf relative water content, whereas it increased endogenous nitric oxide (NO), nitric oxide synthase (NOS), electrolyte leakage (EL), hydrogen peroxide (H2O2), malondialdehyde (MDA) and leaf B content. Reductions in total dry matter were 33% and 61% of control in cvs. Pandas and Altintoprak, respectively. Exogenous application of TU improved the plant growth attributes and led to further increases in NO in the leaves. An additional experiment was set up to further understand whether or not TU mediated NO production played a significant role in mitigation of BT using 0.1 mM scavenger of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO) combined with the TU treatments by spraying once a week for 4 weeks. TU-induced BT tolerance was totally eliminated by cPTIO by reversing endogenous NO levels. BT enhanced the activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC. 1.11.1.6), peroxidase (POD; EC. 1.11.1.7) and lipoxygenase (LOX; EC. 1.12.11.12) as well as the contents of soluble sugars (SS), soluble proteins and phenols, but decreased NR. TU treatments enhanced enzyme activities, but reduced contents of soluble sugars (SS), soluble protein and phenols. The present results clearly indicate that TU mediated endogenous NO significantly improved BT tolerance of wheat plants. This evidence was also supported by the increase in hydrogen peroxide (H2O2) and malondialdehyde (MDA) as well as plant growth inhibition with the application of TU combined with cPTIO. [ABSTRACT FROM AUTHOR]

Oat (Avena sativa) plants grown under 60% field capacity (water-deficit stress) were subjected to proline (40 mM) applied as a foliage spray. Water-deficit conditions suppressed plant growth, chlorophyll contents, leaf vascular bundle area, leaf phloem area and leaf midrib thickness, root diameter, root cortex thickness, stem diameter, stem vascular bundle area and stem phloem area. In contrast, water stress caused an increase in leaf proline, hydrogen peroxide, activities of peroxidase and superoxide dismutase enzymes, leaf bulliform cell area, leaf adaxial epidermis thickness, leaf sclerenchyma thickness, root metaxylem area, root epidermis and endodermis area, root stelar diameter, stem sclerenchyma thickness and stem epidermis thickness. However, exogenous application of proline significantly improved the plant growth, leaf proline contents, metaxylem area, mesophyll thickness, root diameter, root cortex thickness, root epidermis, endodermis thickness, stelar diameter, metaxylem area, stem diameter, stem vascular bundle area, stem epidermis area, stem phloem area and stem sclerenchyma thickness. Overall, foliar spray of proline was effective in improving drought stress tolerance which can be attributed to proline-induced significant modulations in physio-biochemical and anatomical features of oat plants. [ABSTRACT FROM AUTHOR]

Main conclusion: Primitive wheat follows an opposite metabolic law from modern wheat with regard to leaf biomass/reproductive growth vs above-ground biomass that is under the regulation of non-hydraulic root signals and that influences resource acquisition and utilization. Non-hydraulic root signals (nHRS) are so far affirmed as a unique positive response to drying soil in wheat, and may imply huge differences in energy metabolism and source–sink relationships between primitive and modern wheat species. Using a pot-culture split-root technique to induce nHRS, four primitive wheat genotypes (two diploids and two tetraploids) and four modern wheat ones (released from different breeding decades) were compared to address the above issue. The nHRS was continuously induced in drying soil, ensuring the operation of energy metabolism under the influence of nHRS. We found that primitive wheat followed an opposite size-dependent allometric pattern (logy = αlogx + logβ) in comparison with modern wheat. The relationships between ear biomass (y-axis) vs above-ground biomass (x-axis), and between reproductive biomass (y-axis) and vegetative (x-axis) biomass fell into a typical allometric pattern in primitive wheat (α > 1), and the nHRS significantly increased α (P < 0.01). However, in modern wheat, they turned to be in an isometric pattern (α ≈ 1). Regardless of nHRS, either leaf (i.e., metabolic rate) or stem biomass generally exhibited an isometric relationship with above-ground biomass in primitive wheat (α ≈ 1), while in modern wheat they fell into an allometric pattern (α > 1). Allometric scaling of specific leaf area (SLA) or biomass density showed superior capabilities of resource acquisition and utilization in modern wheat over primitive ones. We therefore proposed a generalized model to reveal how modern wheat possesses the pronounced population yield advantage over primitive wheat, and its implications on wheat domestication. [ABSTRACT FROM AUTHOR]

Trehalose is a natural non-reducing sugar that is found in the vast majority of organisms such as bacteria, yeasts, invertebrates and even in plants. Regarding its features, it is considered as a unique compound. It plays a key role as a carbon source in lower organisms and as an osmoprotectant or a stabilizing molecule in higher animals and plants. Although in plants it is present in a minor quantity, its levels rise upon exposure to abiotic stresses. Trehalose is believed to play a protective role against different abiotic stressful cues such as temperature extremes, salinity, desiccation. Moreover, it regulates water use efficiency and stomatal movement in most plants. Detectable endogenous trehalose levels are vital for sustaining growth under stressful cues. Exogenously applied trehalose in low amounts mitigates physiological and biochemical disorders induced by various abiotic stresses, delays leaf abscission and stimulates flowering in crops. External application of trehalose also up-regulates the stress responsive genes in plants exposed to environmental cues. The genetically modified plants with trehalose biosynthesis genes exhibit improved tolerance against stressful conditions. An increased level of trehalose has been observed in transgenic plants over-expressing genes of microbial trehalose biosynthesis. However, these transgenic plants display enhanced tolerance to heat, cold, salinity, and drought tolerance. Due to multiple bio-functions of this sugar, it has gained considerable ground in various fields. However, exogenous use of this bio-safe sugar would only be possible under field conditions upon adopting strategies of low-cost production of trehalose. In short, trehalose is a unique chemical that preserves vitality of plant life under harsh ecological conditions. Certainly, the new findings of this disaccharide will revolutionize a wide array of new avenues. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 L.) plants as well as the mitigating effect of kinetin (KIN) and indole acetic acid (IAA) on these phenomena. Plants of maize cv. DK 647 F1 were exposed to 0.05 and 2 mM boron in nutrient solution 8 days after germination, and the plants were grown for a further 7 days in these conditions. After 15 days growth, deionized water (control), 1.0 or 2.0 mM of KIN, or IAA were applied to the leaves of maize plants once each 7 days. After 21 days of these treatments, the plants were harvested to evaluate growth, water relations, and oxidative and antioxidative systems. Boron toxicity significantly reduced dry matter, efficiency of photosystem II (Fv/Fm), and leaf relative water content in the maize plants when compared to those in non-stressed plants, but in contrast, it enhanced electrolyte leakage (EL), hydrogen peroxide (H2O2), free proline, malondialdehyde (MDA) and the activities of peroxidase, superoxide dismutase, and catalase in the maize plants. However, KIN or IAA applied as a foliar spray to maize plants grown at excess B caused a significant improvement in growth attributes, plant water status and the activities of various antioxidant enzymes as well as proline content, but they lowered EL, and H2O2 and MDA contents. Boron toxicity increased leaf B and reduced leaf K+, Ca2+, and P contents when compared to those in the control plants. Foliar applied KIN or IAA to the plant leaves lowered tissue B levels, but in contrast, it resulted in significant increases in Ca2+, K+ and P levels. The results of the study indicated that the spray of KIN and IAA, particularly at 2 mM, can mitigate to a significant extent the adverse effects of B toxicity on maize plants, which was found be associated with reduced content of B, H2O2, MDA as well as EL, and increased activities of key antioxidant enzymes in maize plants. [ABSTRACT FROM AUTHOR]

In the present experiment, we aimed to test the impact of hydrogen sulfide (H2S) on growth, key oxidant such as hydrogen peroxide, mineral elements, and antioxidative defense in Capia-type red sweet pepper (Capsicum annuum L.) plants subjected to high concentration of zinc (Zn). A factorial experiment was designed with two Zn levels (0.05 and 0.5 mM) and 0.2 mM sodium hydrosulfide (NaHS) as a donor of H2S supplied in combination plus nutrient solution through the root zone. High level of Zn led to reduce dry mass, chlorophyll pigments, fruit yield, leaf maximum fluorescence, and relative water content, but enhanced endogenous hydrogen peroxide (H2O2), free proline, malondialdehyde (MDA), electrolyte leakage (EL), H2S, as well as the activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) enzymes. Exogenously applied NaHS significantly enhanced plant growth, fruit yield, water status, the levels of H2S and proline as well as the activities of different antioxidant enzymes, while it significantly suppressed EL, MDA, and H2O2 contents in the pepper plants receiving low level Zn. NaHS application to the control plants did not significantly change all these parameters tested except the dry matter which increased significantly. High Zn regime led to increase intrinsic Zn levels in the leaves and roots, but it lowered leaf nitrogen (N), phosphorus (P), and iron (Fe) concentrations. However, NaHS reduces the Zn conc. and enhances Fe and N in leaf and root organs. It can be concluded that NaHS can mitigate the harmful effects of Zn on plant growth particularly by lowering the concentrations of H2O2, Zn, EL, and MDA, and enhancing the activities of enzymatic antioxidants and levels of essential nutrients in pepper plants. [ABSTRACT FROM AUTHOR]

To minimize the damaging effects of stresses, plant growth regulators (PGRs) are widely used to sustain the plant life under stress-prone environments. So, a study was carried out to evaluate the response of two canola ( Brassica napus L.) cultivars, Dunkeld and Cyclone, to foliar-applied two potential PGRs, nitric oxide (NO) and 5-aminolevulinic acid, under water deficit conditions. In this study, the levels of NO and ALA used were 0.02 and 0.895 mM, respectively. Plants of both canola cultivars were subjected to control (100% field capacity) and water deficit (60% field capacity). Drought stress significantly decreased growth, chlorophyll pigments, relative water contents (RWC), and soluble proteins, while it increased relative membrane permeability (RMP), proline, glycinebetaine (GB), malondialdehyde (MDA), total phenolics, and activities of catalase (CAT) and peroxidase (POD) enzymes in both cultivars. Foliar application of PGRs improved growth, chlorophyll a, GB, total phenolics, CAT activity, and total soluble proteins, while it decreased RMP, MDA, and POD activity in both canola cultivars. Other physio-biochemical attributes such as chlorophyll b, RWC, hydrogen peroxide (HO) and proline contents as well as superoxide dismutase (SOD) activity remained unaffected due to application of PGRs. So, the results of the present study suggest that exogenous application of NO and ALA could be useful to enhance the drought tolerance of canola plants by up-regulating the oxidative defense system, osmoprotectant accumulation, and minimizing the lipid peroxidation. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is a biologically non-essential, carcinogenic and toxic heavy metal. The cultivation of Cr-tolerant genotypes seems the most favorable and environment friendly strategy for rehabilitation and remediation of Cr-contaminated soils. To prove this hypothesis and identify the Cr tolerance, the present study was performed to assess the physiological and biochemical response of sunflower genotypes to Cr stress. The seeds of six sunflower hybrids, namely FH-425, FH-600, FH-612, FH-614, FH-619, and FH-620, were grown in spiked soil for 12 weeks under increasing concentrations of Cr (0, 5, 10, and 20 mg kg). A seed germination test was also run under different concentrations of Cr (0, 5, 10, 200 mM) in petri dishes. Plants were harvested after 12 weeks of germination. Different plant attributes such as growth; biomass; photosynthesis; gas exchange; activity of antioxidant enzymes, i.e., superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate (APX), and catalases (CAT); reactive oxygen species (ROS); lipid peroxidation; electrolyte leakage; and Cr concentration as well as accumulations in all plant parts were studied for the selection of the most Cr-tolerant genotype. Increasing concentration of Cr in soil triggered the reduction of all plant parameters in sunflower. Cr stress increased electrolyte leakage and production of reactive oxygen species which stimulated the activities of antioxidant enzymes and gas exchange attributes of sunflower. Chromium accumulation in the root and shoot increased gradually with increasing Cr treatments and caused reduction in overall plant growth. The accumulation of Cr was recorded in the order of FH-614 > FH-620 > FH-600 > FH-619 > FH-612 > FH-425. The differential uptake and accumulation of Cr by sunflower hybrids may be useful in selection and breeding for Cr-tolerant genotypes. [ABSTRACT FROM AUTHOR]

Drought is believed to cause many metabolic changes which affect plant growth and development. However, it might be mitigated by various inorganic substances, such as nitrogen. Thus, the study was carried out to investigate the effect of foliar-applied urea with or without urease inhibitor N-( n-butyl) thiophosphoric triamide (NBPT) on a maize cultivar under drought stress simulated by 15% (w/v) polyethylene glycol 6000. Foliar-applied urea resulted in a significant increase in plant dry weight, relative water content, and photosynthetic pigments under water stress condition. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), and hydrogen peroxidase (CAT), were enhanced with all spraying treatments under drought stress, which led to decreases in accumulation of hydrogen peroxide (HO), superoxide anion ( $${\text{O}}_2^{ \cdot - }$$ ) and malondialdehyde (MDA). The contents of soluble protein and soluble sugar accumulated remarkably with urea-applied under drought stress condition. Moreover, a further enhancement in above metabolites was observed by spraying a mixture of urea and urease inhibitor as compared to urea sprayed only. Taken together, our findings show that foliar application of urea and a urease inhibitor could significantly enhance drought tolerance of maize through protecting photosynthetic apparatus, activating antioxidant defense system and improving osmoregulation. [ABSTRACT FROM AUTHOR]

Bio-concentration of elements such as Mo, As, Se, Fe, Cu, Zn, Ni and Pb was analyzed in spring onion ( Allium fistulosum L.) in three different locations of central Punjab, Pakistan. At location GW, relatively low level of hazardous elements was found in spring onion, suggesting that groundwater is a safe source of water for irrigating food crops. The pH of soil at wastewater irrigation was found less acidic (pH 7.4) than the other sites. The range of concentration in the different samples of spring onion was as follows: 6.15-8.16 mg kg for Mo, 2.77-4.28 mg kg for As, 0.395-0.705 mg kg for Se, 36.73-48.17 mg kg for Fe, 10.58-16.26 mg kg for Cu, 28.87-39.79 mg kg for Zn, 6.66-8.75 mg kg for Ni and 4.33-6.09 mg kg for Pb, respectively. High bio-concentration of Zn (15.37) from soil to spring onion was found at canal water irrigated location. The estimated daily intake of metal for spring onion was less, but the health risk index was higher than 1 for Mo, As, Cu, Pb and Ni, respectively. This was due to higher proportion of spring onion in diet, which consequently increased the health risk index for metals. Therefore, it is recommended to avoid growing vegetables in untreated urban and rural wastewater containing elevated amounts of metals. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is among the most toxic pollutants in the environment that adversely affect the living organisms and physiological processes in different plants. The present study investigated the effect of 15 mg L of 5-aminolevulinic acid (ALA) on morpho-physiological attributes of cauliflower ( Brassica oleracea botrytis L.) under different Cr concentrations (0, 10, 100, and 200 μM) in the growth medium. The results showed that Cr stress decreased the growth, biomass, photosynthetic, and gas exchange parameters. Chromium stress enhanced the activities of enzymatic antioxidants, catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) in response to oxidative stress caused by the elevated levels of malondialdehyde (MDA), hydrogen peroxide (HO), and electrolyte leakage (EL) in both roots and leaves of cauliflower. Chromium concentrations and total Cr uptake were increased in leaves, stems, and roots with increasing Cr levels in the culture medium. Foliar application of ALA increased the plant growth parameters, biomass, gas exchange parameters, and photosynthetic pigments under Cr stress compared to the treatments without ALA. Foliar application ALA decreased the levels of MDA, EL, and HO while further improved the performance of antioxidant in both leaves and roots compared to only Cr-stressed plant. Chromium concentrations and total Cr uptake were decreased by the ALA application compared to treatments without ALA application. The results of the present study indicated that foliar application of ALA might be beneficial in minimizing Cr uptake and its toxic effects in cauliflower. [ABSTRACT FROM AUTHOR]

In the present study, levels of trace metals in two commonly consumed vegetables (Spinacia oleracea and Brassica campestris) were assessed. Both vegetables are cultivated in a semi-arid area which receives effluents from various sources. Leafy parts and tender stems are used for human consumption as well as for farm animals as a source of nourishment. However, the aim of the present study was to appraise the concentrations of trace metals in different tissues of both vegetables at the time of harvesting when they become accessible to the humans. The analysis showed that mean trace metal levels in the stem of S. oleracea showed the highest bioconcentration of Zn (25.43 mg kg−1), while in the stem (28.56 mg kg−1) and roots (22.40 mg kg−1), Fe level was the highest. In case of B. campestris, Fe level was highest (18.45 mg kg−1) in the stems. Copper (Cu) has the highest bioconcentration factor values (BF = 1.030) in the stem of B. campestris, whereas Mn (BF = 0.010) was the least accumulated element in the leaves and roots of B. campestris. Collectively, bioconcentration of trace metals in plant tissues exceeded the standard values set by the World Health Organization (WHO) and the US Environmental Protection Agency. So, the vegetables cultivated in effluent-impacted areas may stance a potential public health risk for end-consumers. [ABSTRACT FROM AUTHOR]

High levels of heavy metals in the vegetables are seriously influencing the ecosystem as well as causing many health glitches. Due to many factors like, discharge of untreated industrial effluent, mine tailing, fertilizer application and irrigation with different water sources, the levels of heavy metals increased in soils which further transferred in biological systems. The present study was designed to access bioconcentration of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, and Pb in soils and vegetables (carrots) irrigated with wastewater in Punjab, Pakistan. Result of the study showed that at both study sites concentrations of As and Cd were above the permissible maximum limits (PML). Similarly, concentrations of Mn, Ni, Mo, Cd, and Pb in the vegetable samples of both study sites were higher than maximum permissible limits. Overall, the accumulation of metals (Mn, Ni, Mo, Cd, and Pb) observed in carrots as well as in the soil was beyond the permissible limit that may cause human health disorders for their consumers. [ABSTRACT FROM AUTHOR]

Trehalose, a natural disaccharide, has already been under the attempt of improving stress tolerance in a variety of crop plants. Keeping in view its role in stress tolerance, the effectiveness of seed presoaking with trehalose (25 mM) was tested in radish ( Raphanus sativus L.) plants grown under water stress and non-stress conditions. Two radish cultivars namely Manu and 40-day were grown under control (normal watering) and water-deficit (60 % field capacity) conditions. After 45 days of drought stress treatment, a significant suppression was observed in plant fresh and dry biomass, chlorophyll ( a and b), relative water content (RWC), rate of photosynthesis ( P), sub-stomatal CO concentration ( C), and shoot and root K, Ca and P, while a rise in water-use efficiency (WUE), total soluble sugars (TSS) leaf free proline and glycinebetaine (GB) contents, activities of superoxide dismutase (SOD) and peroxidase (POD) in both radish cultivars under water stress. However, trehalose application caused a significant increase in plant fresh and dry biomass, chlorophyll a content, TSS, P, WUE, free proline contents as well as the activity of SOD enzyme. Of both radish cultivars, cv. Manu was relatively better in chlorophyll b content, TSS and C, while cv. 40-day in shoot K and P contents. However, pattern of decrease or increase was same for all other tested attributes in both radish cultivars. Overall, seed pre-sowing treatment induced growth improvement of radish plants under water stress that was found to be associated with a significant increase in chlorophyll a content, P, WUE, TSS, free proline contents as well as the activity of SOD enzyme in both radish cultivars. [ABSTRACT FROM AUTHOR]

The current research on the manganese (Mn) transfer from soil to plant as well as to grazing Kajli rams in the form of sampling periods was carried out under semi-arid environmental conditions. Forage, soil and blood plasma samples were collected during 4 months of the year after a 1-month interval, and Mn concentrations were assessed after wet digestion using an atomic absorption spectrophotometer. Results showed that Mn concentration in soil ranged from 48.28 to 59.44 mg/kg, with incoherent augment and decline across sampling periods, and effect of sampling period on soil Mn was also found to be significant ( P < 0.05). The mean levels of Mn in soil appeared higher than the critical value and sufficient for forage crop requirement. The Mn concentration in forage ranged between 24.8 and 37.2 mg/kg, resulting deficient based on the requirement allowance of Mn for livestock grazing animals, therein with almost unchanged forage Mn concentration. The Mn values in blood plasma of rams varied from 0.066 to 0.089 mg/l, with a consistent increase based on sampling period, and the effect of sampling periods on plasma Mn was found to be highly significant ( P < 0.05). The Mn levels in ram blood plasma were lesser than the normal level suggesting reasonable need for supplementation. Our study revealed the role of Mn availability in soil and plant species amassing capability on the transport of Mn in the soil-plant-animal system. Results indicated a much higher accumulation rate at the sampling characterized by vegetation dominated by legumes in comparison to grasses, crop residues and mixed pasture and a pronounced seasonal supply of Mn at the four sampling period of grazing land of diverse botanical composition. [ABSTRACT FROM AUTHOR]

A study was conducted to find out the role of ascorbic acid (AsA) in modulating growth and different physio-biochemical attributes of canola plants under well-watered as well as water-deficit conditions. Drought stress imposed on 60 % field capacity significantly decreased the shoot and root fresh and dry weights, leaf chlorophyll contents, shoot and root P, root K, and activity of CAT enzyme, while increased chlorophyll a/b contents, MDA, NPQ, leaf total phenolics, free proline and GB contents in both canola cultivars. Foliar-applied varying levels (50, 100 and 150 mg L) of AsA enhanced shoot and root fresh and root dry weights, qN, NPQ, shoot and root P, AsA as well as the activity of POD enzyme particularly under drought stress conditions. Of both canola cultivars, cv. Dunkeld was higher in shoot fresh weights, ETR and F /F, MDA, proline and GB contents, and POD activity, however, cv. Cyclone in total phenolics and qN under well-watered and water-deficit conditions. Overall, the foliar-applied AsA had a positive effect, though not marked, on salt sensitive cv. Cyclone in terms of improved growth and other attributes, whereas exogenously applied AsA had a non-significant effect on relatively salt tolerant cv. Dunkeld. [ABSTRACT FROM AUTHOR]

Exogenous application of different plant growth regulators is a well-recognized strategy to alleviate stress-induced adverse effects on different crop plants by regulating a variety of physiobiochemical processes such as photosynthesis, chlorophyll biosynthesis, nutrient uptake, antioxidant metabolism, and protein synthesis, which are directly or indirectly involved in the mechanism of stress tolerance. Of various environmental factors, salinity, drought, and extreme temperature (low or high) considerably diminish plant growth and yield by modulating endogenous levels as well as signaling pathways of plant hormones. Of various plant hormones/regulators, a potential plant growth regulator, 5-aminolevulinic acid (ALA), is known to be effective in counteracting the injurious effects of various abiotic stresses in plants. Until now the mechanisms behind ALA regulation of growth under stress have not been fully elucidated. It is also not yet clear how far growth and yield in different crops can be promoted by exogenous application of ALA and whether this ALA-induced growth and yield promotion is cost-effective. Thus, in this review we discuss at length the effects of ALA in regulating growth and development in plants under a variety of abiotic stress conditions, including salinity, drought, and temperature stress. Furthermore, advances in the functional and regulatory interactions of this plant growth regulator with plant stress tolerance, as well as the effective mode of exogenous application of ALA in inducing stress tolerance in plants are also comprehensively discussed in this review. In the future, overaccumulation of ALA in plants through manipulation of gene(s) could enhance plant stress tolerance. Thus, genetic manipulation of plants with the goal of attaining increased synthesis/accumulation of ALA and hence improved stress tolerance under stress conditions is an important area for research. [ABSTRACT FROM AUTHOR]

Gene expression pattern of two important regulatory proteins, salt overly sensitive 2 ( SOS2) and plasma membrane protein 3-1 ( PMP3- 1), involved in ion homeostasis, was analyzed in two salinity-contrasting sunflower ( Helianthus annuus L.) lines, Hysun-38 (salt tolerant) and S-278 (moderately salt tolerant). The pattern was studied at selected time intervals (24 h) under 150 mM NaCl treatment. Using reverse transcription PCR, SOS2 gene fragment was obtained from young leaf and root tissues of opposing lines while that for PMP3- 1 was obtained only from young root tissues. Both tolerant and moderately tolerant lines showed a gradual increase in SOS2 expression in sunflower root tissues. Leaf tissues showed the gradually increasing pattern of SOS2 expression in tolerant plants as compared to that for moderately tolerant ones that showed a relatively lower level of expression for this gene. We found the highest level of PMP 3- 1 expression in the roots of tolerant sunflower line at 6 and 12 h postsalinity treatment. The moderately tolerant line showed higher expression of PMP3- 1 at 12 and 24 h after salt treatment. Overall, the expression of genes for both the regulator proteins varied significantly in the two sunflower lines differing in salinity tolerance. [ABSTRACT FROM AUTHOR]

The present investigation on the iron (Fe) transfer from soil to plant and in turn to animal (cows), as a function of sampling periods was conducted at the Livestock Experimental Station Sargodha, Pakistan which falls under semi-arid conditions. Although the iron transfer from soil to forage increased consistently, the forage Fe content decreased progressively with increase in sampling period. Highest Fe transfer from forage to cow blood plasma was observed during October and lowest during January. The transfer of Fe from forage to animal milk was maximum during the months of October and January and minimum during December. The transfer of Fe to plasma and milk was found to be dependent variably on the growth stage of forage in this investigation. Based on the findings of the present study, it is evident that mineral supplementation with higher Fe availability is urgently warranted to the animals particularly during the months of December and January to enhance plasma Fe in the cows being reared at that livestock farm during the entire grazing period. Thus, obligatory supplementation of Fe to the ruminants is highly recommended. Since the processes involved in iron management system in humans, animals, and plants are basically similar, appropriate elemental management must be provided to the living organisms, otherwise deficient or excessive levels of iron may deteriorate the developing cells of the organisms. [ABSTRACT FROM AUTHOR]

The study was conducted on the cadmium (Cd) transfer from soil to pasture at Khizerabad Livestock Farm, District Sargodha (falling under semi-arid conditions), Pakistan. The concentrations of Cd in the soil and forage ranged from 2.80 to 6.74 mg/kg and 1.14 to 4.20 mg/kg, respectively, in different sampling periods. The higher values of Cd in pasture suggested the possible risk of entering Cd into higher food chain as these concentrations of Cd can potentially be transported from soil to different animals rearing on the farm pastures, and they should be taken into account in risk assessment of chemical toxicity. Providing region-specific mineral mixture having highly bioavailable forms of other trace elements to the ruminants like Zn, Fe, and Mn, which are known to antagonize Cd, would help in overcoming the Cd toxicity. There is an urgent need of permanent monitoring of cadmium content in the feed used in animal nutrition at livestock farm. [ABSTRACT FROM AUTHOR]

Salt-induced changes in growth, photosynthetic pigments, various gas exchange characteristics, relative membrane permeability (RMP), relative water content (RWC) and ion accumulation were examined in a greenhouse experiment on eight sunflower ( Helianthus annuus L.) cultivars. Sunflower cultivars, namely Hysun-33, Hysun-38, M-3260, S-278, Alstar-Rm, Nstt-160, Mehran-II and Brocar were subjected to non-stress (0 mM NaCl) or salt stress (150 mM NaCl) in sand culture. On the basis of percent reduction in shoot biomass, cvs. Hysun-38 and Nstt-160 were found to be salt tolerant, cvs. Hysun-33, M-3260, S-278 and Mehran-II moderately tolerant and Alstar-Rm and Brocar salt sensitive. Salt stress markedly reduced growth, different gas exchange characteristics such as photosynthetic rate ( A), water-use efficiency (WUE) calculated as A/E, transpiration rate ( E), internal CO concentration ( C) and stomatal conductance ( g) in all cultivars. The effect of 150 mM NaCl stress was non-significant on chlorophyll a and b contents, chlorophyll a/b ratio, RWC, RMP and leaf and root Cl, K and P contents; however, salt stress markedly enhanced C /C ratio, free proline content and leaf and root Na concentrations in all sunflower cultivars. Of all cultivars, cv. Hysun-38 was higher in gas exchange characteristics, RWC and proline contents as compared with the other cultivars. Overall, none of the earlier-mentioned physiological attributes except leaf K/Na ratio was found to be effective in discriminating the eight sunflower cultivars as the response of each cultivar to salt stress appraised using various physiological attributes was cultivar-specific. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) has a diverse role in plant metabolism under stressful cues. This study was carried out to evaluate the effectivity of exogenously applied (pre-sowing and foliar) NO to minimize the adversaries of salinity stress on broccoli plants. Experimental design was completely randomized along with four replicates. Two levels of nitric oxide, control (0 mM) and 0.02 mM were applied on broccoli plants subjected to salt stress (120 mM) and non-stress conditions. Data showed that salinity stress significantly reduced fresh or/and dry weights of roots and shoots, root length, chlorophyll (a and b) contents, while it significantly increased total phenolics, hydrogen peroxide (H2O2), malondialdehyde (MDA), glycine betaine, proline, ascorbic acid, activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) enzymes. The external application of NO via both pre-treatment as well as foliar application improved chlorophyll a, total phenolics, glycine betaine, and activities of SOD, CAT and POD enzymes while it was more helpful in lowering levels of H2O2 and MDA, however, it remained ineffective for shoot length. Overall, both modes of NO were effective in improving plant growth, chlorophyll a, proline and glycine betaine contents under stress conditions. The results indicated that external use of NO is beneficial for minimizing the salinity adversaries in broccoli plants. [ABSTRACT FROM AUTHOR]

Main conclusion: Plant osmoprotectants protect against abiotic stresses. Introgression of osmoprotectant genes into crop plants via genetic engineering is an important strategy in developing more productive plants. Plants employ adaptive mechanisms to survive various abiotic stresses. One mechanism, the osmoprotection system, utilizes various groups of low molecular weight compounds, collectively known as osmoprotectants, to mitigate the negative effect of abiotic stresses. Osmoprotectants may include amino acids, polyamines, quaternary ammonium compounds and sugars. These nontoxic compounds stabilize cellular structures and enzymes, act as metabolic signals, and scavenge reactive oxygen species produced under stressful conditions. The advent of recent drastic fluctuations in the global climate necessitates the development of plants better adapted to abiotic stresses. The introgression of genes related to osmoprotectant biosynthesis from one plant to another by genetic engineering is a unique strategy bypassing laborious conventional and classical breeding programs. Herein, we review recent literature related to osmoprotectants and transgenic plants engineered with specific osmoprotectant properties. [ABSTRACT FROM AUTHOR]

The lipophilic vitamin E, α-Tocopherol (α-Toc), has been considered as a potent cellular antioxidant naturally occurring in biological membranes. It plays a number of key metabolic roles in plants exposed to various stressful cues. A field experimental was conducted on mungbean [Vigna radiata (L.) Wilczek] under varying water-limited regimes and the plants were sprayed with four levels of α-Toc (0, 100, 200, and 300 mg L−1) at the vegetative stage of plant growth. The results showed that limited field irrigation regimes (desiccated conditions) caused a marked reduction in growth parameters (shoot and root fresh and dry weights; shoot and root lengths), photosynthetic pigments (chlorophyll a and b), total soluble proteins (TSP) and yield attributes (number of pods, seeds per plant, weight of ripened pods and 100-seeds weight), while, in contrast, water deficiency induced an increase in phenolics, proline, glycine betaine (GB), hydrogen peroxide (H2O2), malondialdehyde (MDA), reducing and non-reducing sugars, total free amino acids, endogenous tocopherol levels, and activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). However, the foliar spray of α-Toc significantly improved shoot and root fresh and dry weights, shoot and root lengths, chlorophyll a and b contents, phenolics, proline, GB, reducing and non-reducing sugars, TSP, total free amino acids, endogenous tocopherol level, and activities of antioxidant enzymes (SOD, POD, and CAT), as well as yield parameters. On the other hand, it significantly decreased the MDA and H2O2 levels. Of all varying levels of α-Toc used, 100 mg L−1 was most effective in causing enhanced accumulation of ascorbic acid (AsA), MDA, and cellular tocopherols particularly in cv. Cyclone 7008, while proline and catalase in cv. Cyclone 8009. Of both cultivars, Cyclone 7008 was superior to the other cultivar in proline, TSP, SOD, and POD enzymes, but cv. Cyclone 8009 being superior in shoot fresh weights, root fresh weight, shoot and root lengths, chlorophyll a and b, phenolics, H2O2, AsA, MDA, CAT, number of pods, seeds, weight of ripened pods, and weight of 100 seeds under dry land conditions. Overall, exogenously applied tocopherol improved yield and myriad of key physio-biochemical attribute in mungbean. [ABSTRACT FROM AUTHOR]