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Stevia (Stevia rebaudiana Bertoni) is an important industrial crop, and its leaves contain steviol glycosides (SGs), which are valuable compounds because they are characterized by a high sweetness and low caloric content. SGs yield depends on nitrogen (N) nutrition; however, the role of N uptake in SGs synthesis needs clarification, especially in organic farming systems that depend on organic and biofertilizers. Plant growth-promoting bacteria (PGPB; i.e., Azospirillum brasilense and Bacillus circulans) and compost were used to study the effect of N nutrition on SGs yield. The experiment consisted of five N treatments with or without PGPB inoculation. The fertilization treatments were: C = without N, T 1 = urea, T 2 = compost, T 3 = urea and compost (75% of N from urea and the rest from compost) and T 4 = urea and compost (50% of N from urea and the rest 50% from compost). Compost and PGPB increased the soil quality indicators and enhanced the synthesis of chlorophyll and nutrient uptake by stevia plants. Mixtures of compost and urea under inoculation with PGPB enhanced soil microbes and enzymatic activity. The highest significant value of nitrogen use efficiency (NUE) resulted from urea alone, while the maximum phosphorus (P) and potassium (K) uptake came from compost. Although urea led to an increase in stevia N uptake, it led to a clear decrease in SGs yield. Urea decreased the total soluble sugar and leaf C/N ratio by 29% and 31%, respectively, compared to those of C. T 4 increased the SGs concentration by 74% and 46%, respectively, compared to that of urea alone in the presence and absence of PGPB. PGPB enhanced the soil quality and promoted nutrient uptake, resulting in significant increases in SGs yield. Regulating N uptake enhanced synthesis of soluble sugars and increased the C/N ratio, which caused an increase in SGs production. The use of compost and plant growth-promoting bacteria is a suitable strategy to produce stevia plants with low rates of inorganic nitrogen without any yield loss. [Display omitted] • Compost and plant growth-promoting bacteria (PGPB) enhances stevia growth. • Compost and PGPB reregulate N-uptake in stevia plants. • Urea decreased the total soluble sugar and leaf C/N ratio. • Regulating N-uptake increased the synthesis steviol glycosides (SGs). • The findings might be an aid for sustainable N management in stevia production. [ABSTRACT FROM AUTHOR]

The elevated level of CO 2 (eCO 2) and arbuscular mycorrhizal fungi (AMF) have been known as successful eco-friendly agents for plant growth and development as well as quality enhancers. The current investigation was designed to study the influence of eCO 2 (620 μmol CO 2 mol−1 air) and AMF on sucrose and phenylpropanoid metabolism, including coumarins, the most important bioactive metabolite in Ammi majus. eCO 2 and AMF were applied, and different parameters have been assessed in A. majus such as changes in mycorrhizal colonization, plant biomass production, photosynthesis, and levels of N, P, and Ca besides the key metabolites and enzymes in sucrose and coumarins metabolic pathways. The present outcomes revealed that eCO 2 and AMF individually or combined enhanced the plant biomass and photosynthesis as well as nutrient concentrations. Furthermore, the levels of sucrose, soluble sugars, glucose, fructose, and the activities of some key enzymes in their metabolism besides phenylpropanoids metabolites in shoot and root of A. majus have been enhanced by eCO 2 and AMF especially when combined. Moreover, upregulation of sucrose is linked to phenylpropanoids metabolic pathway via upregulation of phenylalanine ammonia-lyase activity suggesting high coumarin biosynthesis. Generally, the synergistic effect of both treatments was noted for most of the investigated parameters compared to the individual effect. It could be concluded that the combined application of eCO 2 and AMF affects A. majus global metabolism and induces accumulation of phyto-molecules, coumarin, which might improve its medicinal and pharmacological applications. • eCO 2 and AMF enhanced sucrose and PAL activity in A.majus therefore affects global metabolism and induces coumarin accumulation. [ABSTRACT FROM AUTHOR]

Wadi Namar lake is a new touristic attraction area in the south of Riyadh. Human activities around the lake may lead to changes in water quality with subsequent changes in microenvironment components including microbial diversity. The current study was designed to assess possible changes in bacterial communities of the water at Wadi Namar Lake. Therefore, water samples were collected from three different locations along the lake: L1 (no human activities, no plants), L2 (no human activity, some plants) and L3 (human activities, municipal wastes and some plants). The total DNA of the samples was extracted and subjected to 16S rDNA sequencing and metagenomic analysis; water pH, electrical conductivity (EC), total dissolved solids (TDS) as well as the concentration of Na+1, K+1, Cl−1 and total N were analysed. Metagenomic analysis showed variations in relative abundance of 17 phyla, 31 families, 43 genera and 19 species of bacteria between the locations. Proteobacteria was the most abundant phylum in all locations; however, its highest abundance was in L1. Planctomycete phylum was highly abundant in L1 and L3, while its abundance in L2 was low. The phyla Acidobacteria, Candidatus Saccharibacteria, Nitrospirae and Chloroflexi were associated with high TDS, EC, K+1 and Cl−1 concentrations in L3; various human activities around this location had possibly affected microbial diversity. Current study results help in recognising the structure of bacterial communities at Wadi Namar Lake in relation to their surroundings for planning to environment protection and future restoration of affected ecosystems. [ABSTRACT FROM AUTHOR]

This survey is concerned with the hereditary differences of 29 wild plants collected from fifteen different regions in Al Jubail, Saudi Arabia using two molecular marker systems, viz. inter simple sequence repeat (ISSR) and start codon targeted (SCoT) molecular markers. Ten ISSR and ten SCoT primers amplified a total of 142 and 163 bands with a 87% and 84% polymorphism, respectively. The average number of polymorphic bands for each pair of ISSR and SCoT primers combinations was 12.4 and 13.7, respectively. The highest genetic similarity for ISSR (0.97) and SCoT (0.90) were recognized between Zygophyllum qatarense -22 and Juncus rigidus -23, and between Zygophyllum qatarense -28 and Zygophyllum qatarense -29, whereas the lowest was (0.59) differentiated between Zygophyllum qatarense -6 and Salsola imbricate -18 for ISSR and between Cyperus conglomeratus -7 and Halopeplis perfoliata -14 for SCoT. This considers confirmed the value of molecular techniques such as ISSR and SCoT to assess the hereditary differences among the selected 29 weeds for hereditary preservation and plant enhancement. [ABSTRACT FROM AUTHOR]

Several studies isolated fungal and bacterial species from extreme environments, such as Sabkha and hot deserts, as their natural habitat, some of which are of medicinal importance. Current research aimed investigating the microbial (fungi and bacteria) diversity and abundance in Sabkha and desert areas in Saudi Arabia. Soil samples from nine different geographical areas (Al-Aushazia lake, AlQasab, AlKasar, Tabuk, Al-Kharj, Al-Madina, Jubail, Taif and Abqaiq) were collected and cultured for microbial isolation. Isolated fungi and bacteria were identified by molecular techniques (PCR and sequencing). Based on 18S rDNA sequencing, 203 fungal species belonging to 33 genera were identified. The most common fungal genera were Fusarium , Alternaria , Chaetomium , Aspergillus Cochliobolus and Pencillium , while the most common species were Chaetomium globosum and Fusarium oxysporum. By 16S rDNA sequencing 22 bacterial species belonging to only two genera, Bacillus and Lactobacillus , were identified. The most commonly isolated bacterial species were Bacillus subtilis and Lactobacillus murinus. Some fungal species were confined to specific locations, such as Actinomyces elegans, Fusarium proliferatum, Gymnoascus reesii and Myzostoma spp. that were only isolated from Al-Aushazia soil. AlQasab soil had the highest microbial diversity among other areas with abundances of 23.5% and 4.4% of total fungi, and bacteria, respectively. Findings of this study show a higher degree of fungal diversity than that of bacteria in all studied areas. Further studies needed to investigate the connection between some isolated species and their habitat ecology, as well as to identify those of medicinal importance. [ABSTRACT FROM AUTHOR]

In this work total column ozone (TCO) analysis and variability over globe has been studied during the period 1959–2022 using monthly mean data from ERA5 reanalysis database. The lower values of TCO occurs in equatorial latitudes, while the higher values of TCO appears over the mid-latitude and subpolar latitudes in both hemispheres (slightly farther poleward in the NH). The higher values of the coefficient of variation (CV) of TCO in NH and SH occur over the mid-latitude and subpolar latitudes, it increases gradually latitudinally poleward of 40°N. The lower values of CV appears over tropical and subtropical regions (between 40°S and 40°N). The trend study for the seasonal and annual spatial distribution of TCO divided the globe into three belts the trend values in the first belt (40°N- 90°N) are negative the trend values of TCO in the second belt (40°S- 40°N) are positive (increasing TCO). The third belt (40°S to 90°S) is characterized by the existence of negative trend values of TCO. The study of the Manne Whitney test for abrupt change of the time series of TCO for the three-time series of NHB confirms that there is abrupt change in TCO around the year 1971, 1979, 1992 (increasing) and 2013 (decreasing). • The higher values of TCO appear at mid-latitude and subpolar latitudes in both hemispheres. • The higher values of the coefficient of variation of TCO in NH and SH occur over the mid-latitudes and subpolar latitudes. • The lower values of the coefficient of variation of TCO appear in tropical and subtropical regions. • The trend study for the seasonal and annual TCO divided the globe into three belts. • The trend values in the first and third belts are negative, and positive in the second belt. [ABSTRACT FROM AUTHOR]

Recently, there has been considerable attention towards the production of environmentally friendly nanoparticles (NPs). In this investigation, the successful synthesis of cerium oxide nanoparticles (CeO 2 NPs) was achieved by employing an eco-friendly technique that utilized an extract from the leaves of local plant quinoa (Chenopodium quinoa L.). The synthesized CeO 2 NPs were subjected to characterization using state-of-the-art methods. The prepared CeO 2 NPs contained a round shape with clusters and have a size of 7–10 nm. To assess how effective CeO 2 NPs derived from C. quinoa were against Ustilago tritici , a fungal disease that negatively affects wheat crop globally, a study was performed on two varieties of wheat crop comprised of Arooj (V1) and Akber (V2), cultivated under field conditions. CeO 2 NPs were applied foliarly twice to the wheat crop at four different concentrations: T0 (0 mg/L), T1 (50 mg/L), T2 (75 mg/L), and T3 (100 mg/L). The results revealed that the control group (T0) exhibited the highest disease severity index (DSI) with a value of 75% compared to the other concentrations of CeO 2 NPs on both varieties. At a concentration of 100 mg/L of CeO 2 NPs, the DSI dropped to a minimum of 35% and 37% on both V1 and V2 respectively. These findings indicated that an increase in the concentration of CeO 2 NPs has a beneficial impact on disease severity. Similar patterns have also been observed with disease incidence (DI), with the greatest efficacy observed at a concentration of 100 mg/L of CeO 2 NPs. Our investigation has shown that CeO 2 NPs exhibitd significant antifungal potential against U. tritici which may be a promising strategy to mitigate fungal disease and crop losses globally. [Display omitted] • Chenopodium quinoa leaf extract was used to synthesie CeO 2 NPs • Antifungal potential of CeO 2 NPs was tested in field grown wheat plants • CeO 2 NPs exhibited significant antifungal activity against Ustilago tritici. • CeO 2 NPs could be a promising strategy to combat wheat fungal disease [ABSTRACT FROM AUTHOR]

Industrial activities have led to a gradual and global increase in soil aluminum (Al) and atmospheric CO 2 concentrations. Al bioavailability strongly depends on the soil pH, which in turn is affected by atmospheric CO 2 levels. In spite of the concurrent impact which Al and elevated CO 2 (eCO 2) could have on plants, their interaction and how it might affect the growth of economically important crop species has not been investigated. Here, we have investigated the combined impact of soil Al and eCO 2 exposure on key C3 (wheat, oat) and C4 (maize, sorghum) crops, at the physiological and biochemical level. Compared to C3 plants, C4 plants accumulated less Al by stimulating soil Al retention through exudation of root organic acids. Consequently, Al-exposed C4 plants maintained photosynthetic performance and anti-oxidative capacity. Exposure to eCO 2 reduced the stress responses of C3 and C4 crops to Al exposure. Elevated CO 2 decreased Al accumulation and oxidative damage in all cereals, and ameliorated C3 plant growth. This was reflected on the biochemical level, where eCO 2 inhibited ROS production and restored RuBisCo activity in C3 crops only. Overall, our data suggest that, compared to C3 crops, C4 cereals are more tolerant to soil Al exposure under current ambient CO 2 (aCO 2) levels whereas future eCO 2 levels might stimulate Al tolerance in C3 crops. [Display omitted] • Al differentially accumulated in C3 and C4. • Al differentially induced oxidative damage in C3 and C4. • eCO2 suppressed Al uptake and antagonized its phytotoxicity. • eCO2 inhibited ROS production and restored RuBisCo activity in C3 plants. • C4 plants appear more tolerant to soil Al exposure. [ABSTRACT FROM AUTHOR]

Future climate CO 2 (eCO 2) and contamination with nano-sized heavy metals (HM-NPs) represent concurrent challenges threatening plants. The interaction between eCO 2 and HM-NPs is rarely investigated, and no study has addressed their synchronous impact on the metabolism of the multifunctional stress-related metabolites, such as sugars and amino acids. Moreover, the characteristic responses of C3 and C4 plant systems to the concurrent impact of eCO 2 and HM-NPs are poorly understood. Herein, we have assessed the impact of eCO 2 (620 ppm) and/or HgO-NPs (100 mg/Kg soil) on growth, physiology and metabolism of sugars and amino acids, particularly proline, in C3 (wheat) and C4 (maize) plant systems. Under Hg-free conditions, eCO 2 treatment markedly improved the growth and photosynthesis and induced sugars levels and metabolism (glucose, fructose, sucrose, starch, sucrose P synthase and starch synthase) in wheat (C3) only. In contrast, HgO-NPs induced the uptake, accumulation and translocation of Hg in wheat and to less extend in maize plants. Particularly in wheat, this induced significant decreases in growth and photosynthesis and increases in photorespiration, dark respiration and levels of tricarboxylic acid cycle organic acids. Interestingly, the co-application of eCO 2 reduced the accumulation of Hg and recovered the HgO-NPs-induced effects on growth and metabolism in both plants. At stress defense level, HgO-NPs induced the accumulation of sucrose and proline, more in maize, via upregulation of sucrose P synthase, ornithine amino transferase, ∆1-pyrroline-5-carboxylate (P5C) synthetase and P5C reductase. The co-existence of eCO 2 favored reduced sucrose biosynthesis and induced proline catabolism, which provide high energy to resume plant growth. Overall, despite the difference in their response to eCO 2 under normal conditions, eCO 2 induced similar metabolic events in C3 and C4 plants under stressful conditions, which trigger stress recovery. Unlabelled Image • Under HgO-NPs free conditions, the biofertilization impact of eCO 2 is only evident in wheat (C3). • HgO-NPs increased Hg uptake, accumulation and translocation in the tested plants. • Maize plants (C4) were more tolerant to HgO-NPs toxicity than wheat. • HgO-NPs induced the accumulation of sucrose and proline, more in maize. • Coexistence of eCO 2 with HgO-NPs reduced sucrose biosynthesis and induced proline catabolism in both plants. [ABSTRACT FROM AUTHOR]

Contamination of agricultural fields with bismuth (Bi) reduces crop yield and quality. Arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and crop production, even under stressful conditions such as soil contamination with heavy metals. The objective of this study was to investigate the effect of AMF on the mitigation of Bi-phytotoxicity in wheat (Triticum aestivum) and beans (Phaseolus vulgaris) and to provide a comprehensive evaluation of the physiological and biochemical basis for the growth and development of AMF-induced plants under Bi stress conditions. Wheat and bean were treated by Bi and AMF individually and in combination. Then the physiological and biochemical responses in the shoot and roots of the two crop species were studied. Evident retardations in plant growth and key photosynthesis-related parameters and accumulation of MDA, H 2 O 2 , as markers of oxidative stress, were observed in plants subjected to Bi. AMF colonization reduced the uptake and translocation of Bi in the plant organs by enhancing the exudation of polyphenols and organic acids into the rhizospheric soil. Mycorrhized wheat and bean plants were able to attenuate the effects of Bi by improving metal detoxification (phytochelatins, metallothionein, total glutathione, and glutathione-S-transferase activity) and antioxidant defense systems (both enzymatic and non-enzymatic) and maintaining C assimilation and nutrient status. The current results suggest the manipulation of AMF as a powerful approach to alleviate the phytotoxicity of Bi in legumes and grasses. • Arbuscular mycorrhizal fungi (AMF) stimulate bean, and wheat responses to bismuth (Bi) and alleviate its phytotoxicity. • AMF colonization on wheat and bean reduced Bi uptake by enhancing the exudation of polyphenols and organic acids into the rhizosphere. • AMF colonization improved plant metal detoxification, antioxidant defense systems and maintaining C assimilation and nutrient status. • AMF colonization was more effective in bean than in wheat, as evidenced by lower Bi uptake in bean indicating the influence of plant species in response to stress conditions. [ABSTRACT FROM AUTHOR]

Chromium (Cr) contamination reduces crop productivity worldwide. On the other hand, the expected increase in the future CO 2 levels (eCO 2) would improve plant growth under diverse growth conditions. However, the synergetic effect of eCO 2 has not been investigated at both physiological and biochemical levels in Cr-contaminated soil. This study aims to analyze the mitigating effect of eCO 2 on Cr VI phytotoxicity in two rice cultivars (Giza 181 and Sakha 106). Plants are exposed to different Cr concentrations (0, 200 and 400 mg Cr/kg Soil) at ambient (aCO 2) and eCO 2 (410 and 620 ppm, respectively). Unlike the stress parameters (MDA, H2O2 and protein oxidation), growth and photosynthetic reactions significantly dropped with increasing Cr concentration. However, in eCO 2 conditions, plants were able to mitigate the Cr stress by inducing antioxidants as well as higher concentrations of phytochelatins to detoxify Cr. Notably, the expression levels of the genes involved in mineral nutrition i.e., OsNRAMP1 , OsRT1 , OsHMA3 , OsLCT1 and iron chelate reductase were upregulated in Cr-stressed Giza 181 plants grown under eCO 2. Mainly in Sakha 106, eCO 2 induced ascorbate-glutathione (ASC/GSH)-mediated antioxidative defense system. The present study brings the first ever comprehensive assessment of how future eCO 2 differentially mitigated Cr toxicity in rice. [Display omitted] • Cr exposure induces severe oxidative damage and dysregulates mineral homeostasis. • ECO 2 upregulates the expression of mineral transporter genes in Cr-stressed plants. • ECO 2 modulates the antioxidant defense and metal detoxification systems. • Cultivar-specific responses to the coexistence of Cr and eCO 2 will be noticed. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are beneficial for the plant growth under heavy metal stress. Such beneficial effect is improved by elevated CO 2 (eCO 2). However, the mechanisms by which eCO 2 improves AMF symbiotic associations under arsenite (AsIII) toxicity are hardly studied. Herein, we compared these regulatory mechanisms in species from two agronomical important plant families – grasses (wheat) and legumes (soybean). AsIII decreased plant growth (i.e., 53.75 and 60.29% of wheat and soybean, respectively) and photosynthesis. It also increased photorespiration and oxidative injury in both species, but soybean was more sensitive to oxidative stress as indicated by higher H 2 O 2 accumulation and oxidation of protein and lipid. eCO 2 significantly improved AMF colonization by increasing auxin levels, which induced high carotenoid cleavage dioxygenase (CCDs) activity, particularly in soybean roots. The improved sugar metabolism in plant shoots by co-application of eCO 2 and AsIII allocated more sugars to roots sequentially. Sugar accumulation in plant roots is further induced by AMF, resulting in more C skeletons to produce organic acids, which are effectively exudated into the soil to reduce AsIII uptake. Exposure to eCO 2 reduced oxidative damage and this mitigation was stronger in soybean. This could be attributed to a greater reduction in photorespiration as well as a stronger antioxidant and detoxification defence systems. The grass/legume-specificity was supported by principal component analysis, which revealed that soybean was more affected by AsIII stress and more responsive to AMF and eCO 2. This study provided a mechanistic understanding of the impact of AMF, eCO 2 and their interaction on As-stressed grass and legume plants, allowing better practical strategies to mitigate AsIII phytotoxicity. [Display omitted] • Soybean was more sensitive to As stress but more reponsive to AMF and eCO 2 impact. • High strigolactone biosynthesis by eCO 2 induced AMF colonization, mainly in soybean. • Increased photosynthesis by eCO 2 allocated more sugars to AMF roots of soybean and wheat. • eCO 2 increased soil retention resulting in less As accumulation in AMF treated plants. • eCO 2 strengthen AMF impact on decreasing ROS production and increasing their detoxification. [ABSTRACT FROM AUTHOR]