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Plant growth-promoting bacteria (PGPB) are considered a promising tool for triggering the synthesis of bioactive compounds in plants and to produce healthy foods. This study aimed to demonstrate the impact of PGPB on the growth, accumulation of primary and secondary metabolites, biological activities, and nutritional qualities of Eruca sativa (arugula), a key leafy vegetable worldwide. To this end, Jeotgalicoccus sp. (JW0823), was isolated and identified by using partial 16S rDNA-based identification and phylogenetic analysis. The findings revealed that JW0823 significantly boosted plant biomass production by about 45% (P<0.05) and enhanced pigment contents by 47.5% to 83.8%. JW0823-treated plants showed remarkable improvements in their proximate composition and vitamin contents, with vitamin E levels increasing by 161.5%. JW0823 induced the accumulation of bioactive metabolites including antioxidants, vitamins, unsaturated fatty acids, and essential amino acids, thereby improving the nutritional qualities of treated plants. An increase in the amounts of amino acids was recorded, with isoleucine showing the highest increase of 270.2%. This was accompanied by increased activity of the key enzymes involved in amino acid biosynthesis, including glutamine synthase, dihydrodipicolinate synthase, cystathionine γ-synthase, and phenylalanine ammonia-lyase enzymes. Consequently, the total antioxidant and antidiabetic activities of the inoculated plants were enhanced. Additionally, JW0823 improved antimicrobial activity against several pathogenic microorganisms. Overall, the JW0823 treatment is a highly promising method for enhancing the health-promoting properties and biological characteristics of E. sativa, making it a valuable tool for improving the quality of this important leafy vegetable. [ABSTRACT FROM AUTHOR]

Elevating CO2 (eCO2) levels will change behavior and the effect of soil fertilizers and nutrients. Selenium NPs (SeNPs) have arisen as an alternative to conventional Se fertilizers to enrich crops. However, it remains unclear whether eCO2 will change the biological effects of soil SeNPs on plant growth and metabolism. The current study aimed to shed new light on the interactive impacts of eCO2 and SeNPs on wheat plants. Accordingly, the attempts were to reveal whether the application of SeNPs can modulate the eCO2 effects on wheat (Triticum aestivum L.) physiological and biochemical traits. With this goal, a pot experiment was carried out where the seeds were primed with SeNPs and plants were grown under two levels of CO2 concentrations (ambient CO2 (aCO2, 410 mmol CO2 mol-1; and eCO2 (710 μmol CO2mol-1)) during sixweeks after sowing. Although SeNPs+eCO2 treatment resulted in the highest accumulation of photosynthetic pigment content in leaves (+49-118% higher than control), strong evidence of the positive impacts on Rubisco activity (~+23%), and stomatal conductance (~+37%) was observed only under eCO2, which resulted in an improvement in photosynthesis capacity (+42%). When photosynthesis parameters were stimulated with eCO2, a significant improvement in dry matter production was detected, in particular under SeNPs +eCO2 which was 1.8 times higher than control under aCO2. The highest content of antioxidant enzymes, molecules, and metabolites was also recorded in SeNPs +eCO2, which might be associated with the nearly 50% increase in sodiumcontent in shoots at the same treatment. Taken together, this is the first research documenting the effective synergistic impacts of eCO2 and SeNPs on the mentioned metabolites, antioxidants, and some photosynthetic parameters, an advantageous consequence that was not recorded in the individual application of these treatments, at least not as broadly as with the combined treatment. [ABSTRACT FROM AUTHOR]

Heavy metal pollution is one of the major agronomic challenges. Tungsten (W) exposure leads to its accumulation in plants, which in turn reduces plant growth, inhibits photosynthesis and induces oxidative damage. In addition, the predicted increase in CO2 could boost plant growth under both optimal and heavy metal stress conditions. The aim of the present study was to investigate the effect of W on growth, photosynthetic parameters, oxidative stress and redox status in rye plants under ambient and elevated (eCO2) levels. To this end, rye plants were grown under the following conditions: ambient CO2 (aCO2, 420 ppm), elevated CO2 (eCO2, 720 ppm), W stress (350 mg kg−1 soil) and W+eCO2. W stress induced significant (p < 0.05) decreases in growth and photosynthesis, increases in oxidative damages (lipid peroxidation) and the antioxidant defense system, i.e., ascorbate (ASC), reduced glutathione (GSH), GSH reductase (GR), peroxidase (POX), catalase (CAT), superoxide dismutase (SOD), ASC peroxide (APX) and dehydroascorbate reductase (DHAR). On the other hand, eCO2 decreased W uptake and improved photosynthesis, which sequentially improved plant growth. The obtained results showed that eCO2 can decrease the phytotoxicity risks of W in rye plants. This positive impact of eCO2 on reducing the negative effects of soil W was related to their ability to enhance plant photosynthesis, which in turn provided energy and a carbon source for scavenging the reactive oxygen species (ROS) accumulation caused by soil W stress. [ABSTRACT FROM AUTHOR]

Increases in atmospheric CO2 is known to promote plant growth under heavy metals stress conditions. However, vanadium (V) stress mitigating the impact of eCO2 as well as the physiological and biochemical bases of this stress mitigation have not been well studied. To this end, this study investigated the growth, photosynthetic parameters, oxidative damages antioxidants, and antioxidants enzymes in wheat plants grown under ambient (420 PPM) and high eCO2 (720 ppm) levels. Exposing wheat plants to higher V increased its accumulation in plants which consequentially inhibited plant growth and induced oxidative damage. An increase in antioxidant and detoxification defense systems was observed but it was not enough to reduce V stress toxicity. On the other hand, wheat growth was improved as a result of reduced V uptake and toxicity on photosynthesis under eCO2. To reduce V uptake, wheat accumulated citric acid, and oxalic acid in soil preferentially under both treatments but to more extend under V and eCO2. Additionally, improved photosynthesis induced high carbon availability that was directed to produce chelating proteins (metallothioneins, phytochelatin) and antioxidants (phenolics, flavonoids, total antioxidant capacity). This study advances our knowledge of the processes behind the variations in the physiological and biochemical responses of the wheat crop under V and eCO2 conditions. [ABSTRACT FROM AUTHOR]

Through metabolic analysis, the present research seeks to reveal the defense mechanisms activated by a heavy metals-resistant plant, Sesuvium portulacastrum L. In this regard, shifting metabolisms in this plant were investigated in different heavy metals-contaminated experimental sites, which were 50, 100, 500, 1000, and 5000 m away from a man-fabricated sewage dumping lake, with a wide range of pollutant concentrations. Heavy metals contaminations in contaminated soil and their impact on mineral composition and microbial population were also investigated. The significant findings to emerge from this research were the modifications of nitrogen and carbon metabolisms in plant tissues to cope with heavy metal toxicity. Increased plant amylase enzymes activity in contaminated soils increased starch degradation to soluble sugars as a mechanism to mitigate stress impact. Furthermore, increased activity of sucrose phosphate synthase in contaminated plants led to more accumulation of sucrose. Moreover, no change in the content of sucrose hydrolyzing enzymes (vacuolar invertase and cytosolic invertase) in the contaminated sites can suggest the translocation of sucrose from shoot to root under stress. Similarly, although this study demonstrated a high level of malate in plants exposed to stress, caution must be applied in suggesting a strong link between organic acids and the activation of defense mechanisms in plants, since other key organic acids were not affected by stress. Therefore, activation of other defense mechanisms, especially antioxidant defense molecules including alpha and beta tocopherols, showed a greater role in protecting plants from heavy metals stress. Moreover, the increment in the content of some amino acids (e.g., glycine, alanine, glutamate, arginine, and ornithine) in plants under metal toxicity can be attributed to a high level of stress tolerance. Moreover, strategies in the excitation of the synthesis of the unsaturated fatty acids (oleic and palmitoleic) were involved in enhancing stress tolerance, which was unexpectedly associated with an increase in the accumulation of palmitic and stearic (saturated fatty acids). Taken together, it can be concluded that these multiple mechanisms were involved in the response to stress which may be cooperative and complementary with each other in inducing resistance to the plants. [ABSTRACT FROM AUTHOR]

• P. sativum accessions 200–06 & 200–03 were subjected salinity stress. • Foliar treatment of CTS boosted antioxidant enzyme and enhanced secondary metabolites. • CTS also lowered level of H 2 O 2 and improved the RMP and yield in both pea accessions. • Chitosan treatment further boosted melatonin synthesis. Effects of NaCl stress and foliar treatment of chitosan (CTS) on growth, antioxidant activity, inorganic ions and yield attributes of two pea (Pisum sativum L.) accessions were analyzed in this study. Experimentation was done in total 36 pots with 2 accessions and in three way completely randomized design (CRD) with 3 replicates. P. sativum plants were supplied with three salt concentrations (0, 60 and 120 mM) and two concentrations of CTS (0 and 120 mg/L). Both P. sativum accessions performed notably different from each other under salt stress. On the basis of remarkable reduction in biomass and yield parameters of ccession 200–03 under NaCl stress, it is assumed that this accession might be sensitive against salt stress. Whereas accession 200–06 under NaCl stress showed non-significant reduction in yield and biomass indicating that this accession might be resistant against salt stress. Foliar treatment of CTS boosted antioxidant enzyme activities, enhanced secondary metabolites (leaf proline and total phenolics), lowered the level of H 2 O 2 and improved the RMP and yield in both ccessions. Salt stress resulted in enhanced content of endogenous melatonin. Chitosan treatment further boosted melatonin synthesis. It is concluded that foliar treatment of CTS mitigated the deleterious effects of salt stress and modulated growth in P. sativum plants under salt stress. Therefore, it is recommended that chitosan induced growth modulation in plants may be exploited. [Display omitted] [ABSTRACT FROM AUTHOR]