Bacterial bioaugmentation enhances hydrocarbon degradation, plant colonization and gene expression in diesel-contaminated soil.

Environmental contamination by hydrocarbons is a major problem, and hydrocarbon accumulation in soil poses hazardous threat to ecosystems. Phytoremediation, which involves plants, is an encouraging technique for the removal of hydrocarbons from polluted soil and water. The purpose of this investigation was to examine whether bacterial inoculation enhanced the phytoremediation of hydrocarbons in diesel-contaminated soil vegetated with maize (Zea mays L.). The two cultivars of maize, MMRI Yellow and Pearl White, were planted in diesel-polluted soil (0, 1.5, 2.5, and 3.5 g diesel kg-1 soil), and inoculated with the consortium of three alkane-degrading bacterial strains, Arthrobacter oxydans ITRH49, Pseudomonas sp. ITRI73 and Pseudomonas sp. MixRI75. Bacterial inoculation enhanced plant growth and hydrocarbon degradation. Between two cultivars, MMRI Yellow showed better growth and hydrocarbon degradation in the presence and absence of bacterial inoculation. Maximum hydrocarbon degradation (80%) was observed in the soil having minimum concentration of diesel (1.5 g kg-1 soil), and vegetated with bacterial inoculated MMRI Yellow maize cultivar. Furthermore, more bacterial colonization, and abundance and expression of the alkane hydroxylase gene (alkB) were observed in the root interior than in the rhizosphere and shoot interior of the plants. The bacteria-mediated phytoremediation of soil contaminated with hydrocarbons suggested that the collective use of plants and bacteria was the most beneficial approach for the reclamation of diesel-contaminated soil in comparison with vegetation alone.

Enhancing systematic tolerance in Bermuda grass (Cynodon dactylon L.) through amplified alkB gene expression and bacterial-driven hydrocarbon degradation.

This study aimed to access the impact of soil polluted with petroleum (5, 10 g petroleum kg-1 soil) on Bermuda grass (Cynodon dactylon L.) with and without applied bacterial inoculants (Arthrobacter oxydans ITRH49 and Pseudomonas sp. MixRI75). Both soil and seed were given bacterial inoculation. The evaluated morphological parameters of Bermuda grass were fresh and dry weight. The results demonstrated that applied bacterial inoculants enhanced 5.4%, 20%, 28% and 6.4%, 21%, and 29% shoot and root fresh/dry weights in Bermuda grass under controlled environment. The biochemical analysis of shoot and root was affected deleteriously by the 10 g petroleum kg-1 soil pollution. Microbial inoculants enhanced the activities of enzymatic (catalase, peroxidase, glutathione reductase, ascorbate peroxidase, superoxide dismutase) and non-enzymatic (ɑ-tocopherols, proline, reduced glutathione, ascorbic acid) antioxidant to mitigate the toxic effects of ROS (H2O2) under hydrocarbon stressed condition. The maximum hydrocarbon degradation (75%) was recorded by Bermuda grass at 5 g petroleum kg-1 soil contamination. Moreover, bacterial persistence and alkane hydroxylase gene (alkB) abundance and expression were observed more in the root interior than in the rhizosphere and shoot interior of Bermuda grass. Subsequently, the microbe used a biological tool to propose that the application of plant growth-promoting bacteria would be the most favorable choice in petroleum hydrocarbon polluted soil to conquer the abiotic stress in plants and the effective removal of polyaromatic hydrocarbons in polluted soil.

Induced systemic tolerance mediated by plant-microbe interaction in maize (Zea mays L.) plants under hydrocarbon contamination.

The present investigation was committed to examining the effect of soil spiked with diesel contamination (0, 1.5, 2.5, 3.5 g diesel kg-1 soil) on maize (Zea mays L) varieties (MMRI yellow and Pearl white) with or without bacterial consortium (Pseudomonas aeruginosa BRRI54, Acinetobacter sp. strain BRSI56, Acinetobacter sp. strain ACRH80). Seed and soil bacterial inoculation were done. The studied morphological attributes were fresh and dry weight of shoot and root of both maize varieties. The results documented that bacterial consortium caused 21%, 0.06% and 29%, 34% higher shoot and root fresh/dry weights in "Pearl white" and 14%, 15% and 32%, 22% shoot and root fresh/dry weights respectively in MMRI yellow under control conditions. The biochemical attributes of shoot and root were affected negatively by the 3.5 g diesel kg-1 soil contamination. Bacterial consortium enhanced enzymatic activity (APX, CAT, POD, SOD, GR) and non-enzymatic (AsA, GSH, Pro, α-Toco) antioxidant and reduction in oxidative stress (H2O2, MDA) under hydrocarbon stress as compared to non-inoculated ones in both root and shoot organs. Among both varieties, the highest hydrocarbon removal (75, 64, and 69%) was demonstrated by MMRI yellow with bacterial consortium as compare to Pearl white showed 73, 57, 65% hydrocarbon degradation at 1.5 2.5, 3.5 g diesel kg-1 soil contamination. Consequently, the microbe mediated biotransformation of hydrocarbons suggested that the use of PGPB would be the most beneficial selection in diesel fuel contaminated soil to overcome the abiotic stress in plants and successfully remediation of hydrocarbon in contaminated soil.

Antibiotic use: A cross-sectional survey assessing the knowledge, attitudes, and practices amongst students of Punjab, Pakistan.

Objective: The aim of the study was to assess the knowledge, attitudes and practices of students regarding the use of antibiotics in Punjab, Pakistan. Participants: 525 medical and non-medical students from Punjab in Pakistan. Methods: The t-test and ANOVA were used to compare the average response of respondents. Chi-square test was used to measure the association of different elements. Results: The mean age was 20.78 ± 2.10%. About 14% of the students agreed about the appropriateness of antibiotics for viral infections, and 15% of students said they stopped taking the drugs when symptoms subsided. 65.7% of students took antibiotics only when prescribed by a doctor and 54% bought antibiotics without prescription. Statistically significant results were found among the students who had heard about the antibiotic resistance (p < 0.05). Conclusion: This study will help assess the adequacy of current educational campaigns, maximize rationalization of antibiotic use, and minimize gaps in knowledge and attitudes.

Silicon-Induced Mitigation of NaCl Stress in Barley (Hordeum vulgare L.), Associated with Enhanced Enzymatic and Non-Enzymatic Antioxidant Activities.

Salt stress obstructs plant's growth by affecting metabolic processes, ion homeostasis and over-production of reactive oxygen species. In this regard silicon (Si) has been known to augment a plant's antioxidant defense system to combat adverse effects of salinity stress. In order to quantify the Si-mediated salinity tolerance, we studied the role of Si (200 ppm) applied through rooting media on antioxidant battery system of barley genotypes; B-10008 (salt-tolerant) and B-14011 (salt-sensitive) subjected to salt stress (200 mM NaCl). A significant decline in the accumulation of shoot (35-74%) and root (30-85%) biomass was observed under salinity stress, while Si application through rooting media enhancing biomass accumulation of shoots (33-49%) and root (32-37%) under salinity stress. The over-accumulation reactive oxygen species i.e., hydrogen peroxide (H2O2) is an inevitable process resulting into lipid peroxidation, which was evident by enhanced malondialdehyde levels (13-67%) under salinity stress. These events activated a defense system, which was marked by higher levels of total soluble proteins and uplifted activities of antioxidants enzymatic (SOD, POD, CAT, GR and APX) and non-enzymatic (α-tocopherol, total phenolics, AsA, total glutathione, GSH, GSSG and proline) in roots and leaves under salinity stress. The Si application through rooting media further strengthened the salt stressed barley plant's defense system by up-regulating the activities of enzymatic and non-enzymatic antioxidant in order to mitigate excessive H2O2 efficiently. The results revealed that although salt-tolerant genotype (B-10008) was best adopted to tolerate salt stress, comparably the response of salt-sensitive genotype (B-14011) was more prominent (accumulation of antioxidant) after application of Si through rooting media under salinity stress.

Methyl Jasmonate Alleviated the Adverse Effects of Cadmium Stress in Pea (Pisum sativum L.): A Nexus of Photosystem II Activity and Dynamics of Redox Balance.

The accumulation of cadmium (Cd) in leaves reduces photosynthetic capacity by degrading photosynthetic pigments, reducing photosystem II activity, and producing reactive oxygen species (ROS). Though it was demonstrated that the application of Methyl Jasmonate (MeJA) induces heavy metal (HM) stress tolerance in plants, its role in adjusting redox balance and photosynthetic machinery is unclear. In this study, the role of MeJA in modulating photosystem II (PSII) activity and antioxidant defense system was investigated to reduce the toxic effects of Cd on the growth of pea (Pisum sativum L.) cultivars. One-week-old seedlings of three pea varieties were subjected to Cd stress (0, 50, 100 µm), and MeJA (0, 1, 5, 10 µm) was applied as a foliar spray for 2 weeks. Cadmium stress reduced the growth of all three pea varieties. Cadmium stress decreased photosynthetic pigments [Chl a (58.15%), Chl b (48.97%), total Chl (51.9%) and carotenoids (44.01%)] and efficiency of photosystem II [Fv/Fm (19.52%) and Y(II; 67.67%)], while it substantially increased Cd accumulation along with an increase in ROS (79.09%) and lipid peroxidation (129.28%). However, such adverse effects of Cd stress varied in different pea varieties. Exogenous application of MeJA increased the activity of a battery of antioxidant enzymes [superoxide dismutase (33.68%), peroxidase (29.75%), and catalase (38.86%)], improved photosynthetic pigments and PSII efficiency. This led to improved growth of pea varieties under Cd stress, such as increased fresh and dry weights of shoots and roots. In addition, improvement in root biomass by MeJA was more significant than that of shoot biomass. Thus, the mitigating effect of MeJA was attributed to its role in cellular redox balance and photosynthetic machinery of pea plants when exposed to Cd stress.

Lead contamination affects the primary productivity traits, biosynthesis of macromolecules and distribution of metal in durum wheat (Triticumdurum L.).

Lead (Pb) pollution emerged as an international issue particularly during second and third industrial revolution and is of serious global concern. Cereal crops have shown different capabilities, innate variability and mechanisms to cope with heavy metals present in their environment. Keeping in view the perspectives of food security and safety with increasing demand for Triticum durum L. it becomes imperative to appraise sustainability potential of the crop for Pb contaminated soils. The current study was conducted to test the hypothesis that T. durum germplasm holds genetic variability to evolve under Pb contamination through modulations of morpho-biochemical parameters of selective advantage. The performance of nine T. durum L. cultivars (CBD25, CBD46, CBD58, CBD59, CBD63, CBD66, CBD68, CBD69 and CBD82) was evaluated following exposure to varying Pb levels (control, 10, 20 and 40 mg kg-1) in soil. Growth, biosynthesis of macromolecules and metal distribution in plant parts were assessed using valid procedures and protocols. The cultivars exhibited a differential degree of tolerance to Pb and among the tested germplasm, CBD59 performed better followed by CBD63 and CBD66 for their primary productivity traits, biosynthesis of pigments and other macromolecules (amino acids, proteins and sugar) along with resilience for Pb uptake and its consequent bioaccumulation in grains. The traits used in the study served as strong predictors to provide superior/selective ability to survive under contaminated environment. The study signified that metal tolerance/sensitivity in the cultivars is independent of magnitude of metal stress, growth responses and Pb accumulation in plant parts hence varied in space and time. The existence of genetic variability, which is a pre-requisite for selection can definitely be of great advantage for future breeding projects to develop high yielding varieties/ cultivars of durum wheat with Pb free grains to assure food security and safety.

Foliar fertigation of ascorbic acid and zinc improves growth, antioxidant enzyme activity and harvest index in barley (Hordeum vulgare L.) grown under salt stress.

Crop productivity is limited by several environmental constraints. Among these, salt stress plays a key role in limiting the growth and yield production of economically important agricultural crops. However, the exogenous fertigation of vitamins and minerals could serve as a "shot-gun" approach for offsetting the deleterious effects of salts present in the rhizosphere. Therefore, an experiment was conducted to quantify the efficacy of foliar fertigation of ascorbic acid (vitamin-C) and zinc (Zn) on the physio-biochemical attributes of barley (Hordeum vulgare L. Genotype B-14011) grown in a saline environment. The salt stress resulted in a reduced biological yield associated with a decrease in chlorophyll pigment, while a significant enhancement in Na+ and Zn2+ was observed under salinity stress. Similarly, the contents of total soluble proteins, total free amino acids, lipid peroxidation, and H2O2 and the activities of antioxidative enzymes (SOD, POD, CAT, APX and proline) were significantly enhanced under salinity stress. Moreover, salinity negatively affected the yield attributes and ion uptake of plants. However, foliar fertigation with AsA +0.03% Zn enhanced vegetative growth, photosynthetic pigments, synchronized ion uptake, the synthesis of enzymatic and non-enzymatic antioxidants, and the harvest index. It is inferred from this study that among all treatments, the effect of foliar fertigation with the AsA+0.03% Zn combination not only improved the salt stress tolerance but also improved the yield attributes, which will aid in the improvement in barley seed yield and is a step to solve the problem of malnutrition through biofortification of vitamin-C and zinc.

Identification of novel source of salt tolerance in local bread wheat germplasm using morpho-physiological and biochemical attributes.

Salt tolerant wheat cultivars may be used as genetic resource for wheat breeding to ensure yield stability in future. The study was aimed to select salt tolerant cultivar(s) to identify novel source of salt tolerance in local wheat germplasm. Initially, 40 local wheat cultivars were screened at 150 mM NaCl stress at seedling stage. Selected salt-tolerant (three; S-24, LU-26S and Pasban-90) and salt-sensitive (four; MH-97, Kohistan-97, Inqilab-91 and Iqbal-2000) wheat cultivars were further evaluated using growth, yield, biochemical and physiological attributes. Growth and yield of selected cultivars were reduced under salt stress due to decline in plant water status, limited uptake of macronutrients (N, P and K), reduced K+/Na+ ratio, photosynthetic pigments and quantum yield of PSII. Wheat plants tried to acclimate salt stress by osmotic adjustment (accumulation of total soluble sugars, proline and free amino acids). Degree of salinity tolerance in cvs. S-24 and LU-26S found to be associated with maintenance of K+/Na+ ratio, osmo-protectant and photosynthetic activity and can be used as donor for salt tolerance in wheat breeding program at least in Pakistan. These cultivars can be further characterized using molecular techniques to identify QTLs/genes for salt exclusion, osmo-protectant and photosynthetic activity for molecular breeding.

Modulation of salt (NaCl)-induced effects on oil composition and fatty acid profile of sunflower (Helianthus annuus L.) by exogenous application of salicylic acid.

BACKGROUND: Salicylic acid (SA) is a potential endogenous plant hormone that plays an important role in plant growth and development. Since sunflower yield and its seed oil yield are adversely affected by salinity, in this study the role of SA in modulating salt (NaCl)-induced effects on various yield and oil characteristics of sunflower was investigated. For this purpose a greenhouse experiment comprising two sunflower hybrid lines (Hysun-33 and SF-187), two NaCl levels (0 and 120 mmol L(-1)) and four SA levels (0, 100, 200 and 300 mg L(-1)) was conducted. RESULTS: Salt stress markedly reduced yield, oil content, linoleic acid and δ-tocopherol in both sunflower lines, while it increased linolenic acid, palmitic acid, stearic acid and α- and γ-tocopherols. However, increasing levels of foliar-applied SA resulted in improved achene yield and hundred-achene weight in both lines. Foliar-applied SA caused a significant decrease in oil stearic acid and α- and γ-tocopherols in both lines under non-saline and saline conditions. CONCLUSION: Salt-induced harmful effects on achene yield and oil characteristics of sunflower could be alleviated by exogenous application of SA. High doses of SA caused a marked increase in sunflower achene oil content as well as some key fatty acids.

Tomato Plant Proteins Actively Responding to Fungal Applications and Their Role in Cell Physiology.

The pattern of protein induction in tomato plants has been investigated after the applications of pathogenic and non-pathogenic fungal species. Moreover, particular roles of the most active protein against biological applications were also determined using chromatographic techniques. Alternaria alternata and Penicillium oxalicum were applied as a pathogenic and non-pathogenic fungal species, respectively. Protein profile analysis revealed that a five protein species (i.e., protein 1, 6, 10, 12, and 13) possessed completely coupled interaction with non-pathogenic inducer application (P. oxalicum). However, three protein species (i.e., 10, 12, and 14) recorded a strong positive interaction with both fungal species. Protein 14 exhibited the maximum interaction with fungal applications, and its role in plant metabolism was studied after its identification as protein Q9M1W6. It was determined that protein Q1M1W6 was involved in guaiacyl lignin biosynthesis, and its inhibition increased the coumarin contents in tomato plants. Moreover, it was also observed that the protein Q9M1W6 takes significant part in the biosynthesis of jasmonic acid and Indole acetic acid contents, which are defense and growth factors of tomato plants. The study will help investigators to design fundamental rules of plant proteins affecting cell physiology under the influence of external fungal applications.