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Plant abiotic stresses endanger crop production and food security to a growing degree under the present climate change scenario. This calls for effective measures to be deployed to increase the level of agricultural production to meet the needs of soaring world population. Application of osmo-protectants and soluble sugars were reported to counter abiotic stresses in many crop species. Trehalose (Tre) is one such non-reducing sugar found in bacteria and yeasts, where it serves as source of carbon, and in higher plants and animals, where it acts as osmo-protectant. Tre is involved in various physiological, biochemical and molecular mechanisms associated with plant growth, development and defense against drought, salinity, cold, heat, UV rays, nutrient deficiency and heavy metal stresses. It helps to maintain cellular integrity under stress by upgrading the antioxidant defense system. However, Tre amounts are lower than those needed to assure adequate plant stress tolerance. Interestingly, Tre supplementation up-regulates stress response genes and induces the accumulation of various osmolytes, including proline, glycine betaine and soluble sugars, which confer different kinds of stress tolerance. Alternatively, the development of transgenic plants with genes for Tre biosynthesis leads to appreciable tolerance against different stresses. However, some transgenic plants over-expressing Tre biosynthesis genes are adversely affected. This work aims to systematically review Tre's role as stress tolerance molecule and its crosstalk with other osmolytes under stress conditions, explaining mechanism of stress tolerance and pointing out areas for future research. It is evidenced that this compound owns a promising future as osmo-protectant in the coming years. The present review is intended as means to enrich the awareness on Tre potential benefits, in order to help the scientists as well as the practitioners to improve crop behavior and ultimate production under stress conditions. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles have recently attained much interest due to the wide distribution of their applications. The current work is concerned with the synthesis of magnetic iron oxide nanoparticles using green and chemical methods. Licorice extract has been used as the main factor for the production of green synthesized magnetic nanoparticles (GSM), compared with the co-precipitation method for the production of chemically synthesized magnetic nanoparticles (CSM). Both scanning electron microscopy (SEM) and particle size analyzer (PSA) proved the formation of the particles in the nanoscale with the range of 50–110 nm and 40–100 nm for GSM and CSM, respectively. Furthermore, Energy-dispersive X-ray spectroscopy (EDX) indicated the existence of iron and oxygen elements in both the samples and proved the formation of iron oxide nanoparticles. Both types of nanoparticles were solely integrated with chitosan for the formation of magnetic-dependent membranes followed by integration-dependent characterization using SEM and Raman spectroscopy. The tensile properties of the membranes showed higher elongation and strain properties of chitosan/GSM membrane compared with plain chitosan or chitosan/CSM membranes, which candidate it for mechanical-dependent applications. The vibrating sample magnetism (VSM) properties showed that GSM nanoparticles are superparamagnetic. In addition, the GSM nanoparticles are applied as methanol electrochemical sensors with high sensitivity even at low concentrations of methanol. [ABSTRACT FROM AUTHOR]

Biobased degradable plastics have received significant attention owing to their potential application as a green alternative to synthetic plastics. A dye-based procedure was used to screen poly-3-hydroxybutyrate (PHB)-producing marine bacteria isolated from the Red Sea, Saudi Arabia. Among the 56 bacterial isolates, Pseudodonghicola xiamenensis, identified using 16S rRNA gene analyses, accumulated the highest amount of PHB. The highest PHB production by P. xiamenensis was achieved after 96 h of incubation at pH 7.5 and 35 °C in the presence of 4% NaCl, and peptone was the preferred nitrogen source. The use of date syrup at 4% (w/v) resulted in a PHB concentration of 15.54 g/L and a PHB yield of 38.85% of the date syrup, with a productivity rate of 0.162 g/L/h, which could substantially improve the production cost. Structural assessment of the bioplastic by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy revealed the presence of methyl, hydroxyl, methine, methylene, and ester carbonyl groups in the extracted polymer. The derivative products of butanoic acid estimated by gas chromatography-mass spectrometry [butanoic acid, 2-amino-4-(methylseleno), hexanoic acid, 4-methyl-, methyl ester, and hexanedioic acid, monomethyl ester] confirmed the structure of PHB. The present results are the first report on the production of a bioplastic by P. xiamenensis, suggesting that Red Sea habitats are a potential biological reservoir for novel bioplastic-producing bacteria. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the efficiency of Enterobacter cloacae PS14 and Trichoderma asperellum T34 in the control of potato wilt, caused by Ralstonia solanacearum (Smith), under greenhouse and field conditions. In vitro, the endophyte E. cloacae PS14 caused the highest reduction of the pathogen growth among 7 screened bacteria. It produced an inhibition zone as 16.9 mm compared to a specific antibiotic (20.0 mm). E. cloacae PS14 was selected as an effective antagonistic bacterium to be compared to T. asperellum strain T34 for reduction of the disease as well as increasing the crop yield of potato plants. Both E. cloacae and T. asperellum reduced the disease severity up to 10.7–26.5%, respectively, under greenhouse and up to 26.6–36.6%, respectively, under field conditions. The results approved that both E. cloacae and T. asperellum increased the yield of the crop by 20.44–40.96%, respectively. Their mode of action was indicated by suppression of the pathogen as well as induction of plant systemic resistance. The induction of systemic resistance was confirmed by increasing the total phenol and salicylic acid contents as well as increasing the activities of peroxidase, lipoxygenase, and polyphenol oxidase in potato plants than the healthy or only infected plants. Production of siderophore, indole-3-acetic acid (0.577–0.884 μM), hydrogen cyanide (2.34–3.61 μg/ml), and salicylic acid (0.436–1.488 μg/ml) was confirmed by E. cloacae PS14 and T. asperellum T34, respectively, in vitro. The study recommends the new strain E. cloacae PS14, as new endophytic effective bacteria, in the control of R. solanacearum causing the potato wilt disease. [ABSTRACT FROM AUTHOR]

Rhizobacteria have been reported as bioagents of bacterial diseases and plant growth promoters. The present in vitro study and greenhouse experiment aimed to evaluate the efficiency of Bacillus subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, and P. aeruginosa for the control of bacterial wilt caused by Clavibacter michiganensis subsp. michiganensis and promoting the growth of tomato plants. Effect of formulated and cell suspensions on disease reduction and the pathogen colonization frequency in plants were assessed. The tested bacterial species were able to inhibit the growth of the causal pathogen in vitro. Under greenhouse conditions, the highest reduction in disease severity was detected in tomato plants treated with formulated B. amyloliquefaciens (74.4%), followed by P. aeruginosa (66.7%), while the lowest reduction occurred in tomato seedlings treated with cell suspensions of P. fluorescens (40%) and B. subtilis (53.3%). The four bacterial species produced siderophores, hydrogen cyanide and indole acetic acid in different concentrations. The study confirmed that the use of the four bacterial species as suspensions or formulations could be applied as future eco-friendly alternatives to the synthetic fungicides for controlling the bacterial wilt of tomato caused by C. michiganensis subsp. michiganensis. [ABSTRACT FROM AUTHOR]