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The present study aimed to investigate the effects of different soil amendments coupled with nitrogen fertilizer on the morpho-physiological characteristics and yield of salt-tolerant rice under saline conditions. The soil amendments, i.e., S1: zeolite amendment, S2: coconut coir amendment, S3: humic acid amendment, and S0: no amendment, and fertilizer treatments, i.e., N1: urea, N2: slow-release urea, and N0: no N fertilizer, were kept in main plots and sub-plots, respectively, in a split-plot design. The salt-tolerant variety 'Shuangliangyou 138' was exposed to 0.3% salt irrigation water. The results showed that during the entire growth period, compared to S0, the S1 and S3 treatments increased the SPAD values by an average of 6.3%and 5.5%, respectively, the leaf area index by an average of 24.5% and 19.8%, the canopy interception rate by an average of 11.5% and 4.1%, and the aboveground biomass by an average of 36.8% and 13.9%, respectively. Moreover, under S1 and S3 conditions, the tiller number per square meter, leaf water potential, leaf water content, and chlorophyll contents were also improved under the slow-release urea than urea. Moreover, slow-release urea promoted root vitality and nutrient absorption as well as enhanced the activity of antioxidant and nitrogen metabolism enzymes than urea under the S1 and S3 conditions. In sum, the rational application of soil amendments and slow-release urea could improve the rice productivity on saline-alkali land. [ABSTRACT FROM AUTHOR]

This study examines nitrogen transformation mechanisms and compost quality in mesophilic aerobic composting of wheat straw, utilizing cow manure as a co-substrate to promote sustainable agricultural waste management. Two composting systems were established: group A (control) and group B (10% cow manure addition by wet weight). The addition of cow manure accelerated early organic matter decomposition and increased total nitrogen retention in group B. Nitrogen losses occurred primarily via ammonia volatilization during the initial and final composting stages, while functional gene analysis revealed enhanced ammonification and nitrification in both systems. Microbial community analysis showed that cow manure addition promoted nitrogen-fixing bacteria in the early phase and fungi associated with complex organic degradation in later stages. These findings underscore the potential of cow manure to enhance compost maturity, improve nitrogen efficiency, and support the development of sustainable composting practices that contribute to resource conservation. [ABSTRACT FROM AUTHOR]

The global shortage of high-quality forage has significantly constrained the development of animal husbandry. Leveraging the complementary effects of forage rapeseed and hairy vetch intercropping can enhance forage yield and quality; however, the underlying mechanisms of overyielding in forage rapeseed–hairy vetch intercropping systems remain unclear. Over two years of field experiments, three cropping systems—rapeseed sole cropping, hairy vetch sole cropping, and rapeseed–hairy vetch intercropping—were investigated to assess the effects of intercropping on root and stem morphology, canopy light distribution, leaf photosynthetic physiology, and nitrogen metabolism. Our results demonstrated that intercropping increased forage biomass and crude protein yield by 14.3–20.0% and 30.7–92.8%, respectively, compared to sole cropping. Intercropping significantly enhanced root biomass, increasing lateral root biomass by 81% compared to rapeseed sole cropping. It also improved stem anatomical traits, including the cortex area (58.8–80.7%), cortex thickness (25.1–38.3%), number of vascular bundles (18.0–37.3%), vascular bundle length (17.8–18.4%), vascular bundle perimeter (6.7–18.7%), vascular bundle area (34.6–63.9%), and stem breaking strength (25.7–76.6%). Additionally, intercropping optimized vertical canopy light interception, reduced the activity of antioxidant enzymes (CAT, POD, SOD) and reactive oxygen species (ROS) accumulation, and enhanced the activities of glutamine synthetase and nitrate reductase, stomatal traits, and photosynthetic rates in the leaves of both crops. Structural equation modeling revealed that, in the intercropping system, improved population lodging resistance directly promoted nitrogen metabolism and leaf photosynthetic rates, ultimately increasing population biomass. In summary, rapeseed–hairy vetch intercropping improved canopy light distribution, strengthened rapeseed stem anatomy and root penetration, and enhanced population lodging resistance, leaf photosynthetic physiology, and nitrogen metabolism, thereby boosting forage biomass and quality. The supportive role of rapeseed in the intercropping system elucidates the overyielding mechanisms of rapeseed–hairy vetch intercropping, offering a theoretical framework for optimizing forage production systems worldwide. [ABSTRACT FROM AUTHOR]

The black garden ant (Lasius niger) is a widely distributed species across Europe, North America, and North Africa, playing a pivotal role in ecological processes within its diverse habitats. However, the microbiome associated with L. niger remains poorly investigated. In the present study, we isolated a novel species, Paenarthrobacter lasiusi, from the soil of the L. niger anthill. The genome of P. lasiusi S21 was sequenced, annotated, and searched for groups of genes of physiological, medical, and biotechnological importance. Subsequently, a series of microbiological, physiological, and biochemical experiments were conducted to characterize P. lasiusi S21 with respect to its sugar metabolism, antibiotic resistance profile, lipidome, and capacity for atmospheric nitrogen fixation, among others. A notable feature of the P. lasiusi S21 genome is the presence of two prophages, which may have horizontally transferred host genes involved in stress responses. P. lasiusi S21 synthesizes a number of lipids, including mono- and digalactosyldiacylglycerol, as well as steroid compounds that are typically found in eukaryotic organisms rather than prokaryotes. P. lasiusi S21 exhibits resistance to penicillins, lincosamides, fusidins, and oxazolidinones, despite the absence of specific genes conferring resistance to these antibiotics. Genomic data and physiological tests indicate that P. lasiusi S21 is nonpathogenic to humans. The genome of P. lasiusi S21 contains multiple operons involved in heavy metal metabolism and organic compound inactivation. Consequently, P. lasiusi represents a novel species with an intriguing evolutionary history, manifesting in distinctive genomic, metabolomic, and physiological characteristics. This species may have potential applications in the bioaugmentation of contaminated soils. [ABSTRACT FROM AUTHOR]

Under NaHCO3 stress, exogenous 24-epibrassinolide (EBR) markedly alleviated Na+ accumulation in cucumber plants, thereby decreasing the Na+/K+, Na+/Mg2+, and Na+/Ca2+ ratios. This mitigation was accompanied by elevated concentrations of K+, Ca2+, and Mg2+, as well as enhanced expression of the NHX and SOS1 genes. In addition, the activities of plasma membrane H+-ATPase, vesicular membrane H+-ATPase, and vesicular membrane H+-PPase were significantly increased, contributing to the maintenance of ionic balance in cucumber plants. NaHCO3 stress disrupted nitrogen metabolism, as evidenced by reductions in the activities of NR, GS, GOGAT, GOT, and GPT, along with altered GDH activity. These disruptions led to an accumulation of NH4+ and substantial decreases in NO3−-N and total nitrogen content. Exogenous EBR alleviated these effects by enhancing the activities of NR, GS, GOGAT, GOT, and GPT, countering the prolonged suppression of GDH activity, and restoring NO3−-N and total nitrogen levels. Consequently, EBR application reduced NH4+ toxicity induced by alkali stress. Additionally, NaHCO3 stress increased ABA accumulation while decreasing IAA and GA3 content in cucumber seedlings. In contrast, exogenous EBR application elevated IAA and GA3 levels and increased the IAA/ABA and GA3/ABA ratios, thus maintaining hormonal equilibrium under alkali stress. Collectively, these findings highlight that exogenous EBR enhances the alkaline tolerance of cucumber plants by regulating nitrogen metabolism, ion homeostasis, and phytohormonal responses. [ABSTRACT FROM AUTHOR]

Melon is a thermophilic crop that is extremely sensitive to temperature changes. Humic acid (HA) is an eco-friendly biostimulant that enhances plants against abiotic stresses. However, the effect of HA on the cold tolerance of melon plants under low-temperature scenarios is still unclear. This study aimed to find out the effects of HA treatment on the morphological, physiological, and nitrogen metabolism of melon seedlings under low-temperature stress. HA treatment significantly enhanced plant height, stem diameter, fresh weight, dry weight, chlorophyll content (up to 33.17%), maximum photochemical efficiency (Fv/Fm), root architecture, superoxide dismutase (SOD), and catalase (CAT) activity. HA also promoted the degradation of nitrate nitrogen (NO3−-N); the synthesis of ammonium nitrogen (NH4+-N), free amino acids, proline, and soluble protein; and nitrogen metabolism (NR, GS, GOGAT, and GDH, up to 181.83%) and proline-related enzyme activity (P5CS and OAT, up to 81.97%). HA significantly increased the expression of nitrogen metabolism and proline metabolism genes. In summary, HA alleviated the damage caused by low-temperature stress by improving levels of antioxidant enzymes, nitrogen metabolism, and proline synthesis. [ABSTRACT FROM AUTHOR]

Drought is the primary limiting factor affecting soybean productivity, and is exacerbated by climate change. In legumes like soybeans, biological nitrogen fixation (BNF) is the main form of nitrogen acquisition, with nitrogen being converted into ureides. A greenhouse experiment was conducted using the soybean cultivar BMX Zeus IPRO, with two water treatments applied during the vegetative phase: control (C) and water deficit (D). The relative water content and number of nodules were reduced in the D plants. Ureide concentrations (allantoin and allantoic acid) were higher in nodules under D conditions. However, no differences were observed in allantoin, total ureide, and soluble sugar concentrations in leaves. Our results suggest that reducing the number of nodules may be a key strategy for maintaining BNF under drought conditions and that ureide accumulation could be the primary metabolic response in this soybean cultivar. These findings indicate that the effects of water restriction on BNF are likely associated with local metabolic responses rather than a systemic ureide feedback mechanism inhibiting BNF. [ABSTRACT FROM AUTHOR]

Phyllostachys edulis, an economically and ecologically significant bamboo species, has substantial research value in applications as a bamboo substitute for plastic and in forest carbon sequestration. However, frequent seasonal low-temperature events due to global climate change affect the growth, development, and productivity of P. edulis. Calcium signaling, serving as a versatile second messenger, is involved in various stress responses and nitrogen metabolism. In this study, we analyzed the calcium signaling dynamics and regulatory strategies in P. edulis under chilling stress. Differentially expressed genes (DEGs) from the CBF families, AMT families, NRT families, and Ca2+ sensor families, including CaM, CDPK, and CBL, were identified using transcriptomics. Additionally, we explored the law of Ca2+ flux and distribution in the roots of P. edulis under chilling stress and validated these findings by assessing the content or activity of Ca2+ sensor proteins and nitrogen transport proteins in the roots. The results indicated that the Ca2+ sensor families of CaM, CDPK, and CBL in P. edulis exhibited significant transcriptional changes under chilling stress. Notably, PH02Gene03957, PH02Gene42787, and PH02Gene19300 were significantly upregulated, while the expressions of PH02Gene08456, PH02Gene01209, and PH02Gene37879 were suppressed. In particular, the expression levels of the CBF family gene PH02Gene14168, a downstream target gene of the calcium channels, increased significantly. P. edulis exhibited an influx of Ca2+ at the root, accompanied by oscillating negative peaks under chilling stress. Spatially, the cytosolic calcium concentration ([Ca2+]cyt) within the root cells increased. The CIPK family genes, interacting with Ca2+-CBL in downstream signaling pathways, showed significant differential expressions. In addition, the expressions of the NRT and AMT family genes changed correspondingly. Our study demonstrates that Ca2+ signaling is involved in the regulatory network of P. edulis under chilling stress. [Ca2+]cyt fluctuations in the roots of P. edulis are induced by chilling stress, reflecting an influx of extracellular Ca2+. Upon binding to Ca2+, downstream target genes from the CBF family are activated. Within the Ca2+–CBL–CIPK signaling network, the CIPK family plays a crucial role in nitrogen metabolism pathways. [ABSTRACT FROM AUTHOR]

Light quality optimization is a cost-effective method for increasing leafy vegetable quality in plant factories. Light-emitting diodes (LEDs) that enable the precise modulation of light quality were used in this study to examine the effects of red-blue (RB), red-blue-green (RBG), red-blue-purple (RBP), and red-blue-far-red (RBF) lights on the growth, antioxidant capacity, and nitrogen metabolism of Chinese cabbage leaves, while white light served as the control (CK). Results showed that the chlorophyll, carotenoid, vitamin C, amino acid, total flavonoid, and antioxidant levels of Chinese cabbage were all significantly increased under RBP combined light treatment. Meanwhile, RBG combined light treatment significantly increased the levels of amino acids but decreased the nitrite content of Chinese cabbage. In addition, RBF combined light treatment remarkably increased the amino acid levels but decreased the antioxidant capacity of Chinese cabbage. In conclusion, the addition of purple light to red-blue light was effective in improving the nutritional value and antioxidant capacity of Chinese cabbage. This light condition can be used as a model for a supplemental lighting strategy for leafy vegetables in plant factory production. [ABSTRACT FROM AUTHOR]

This study investigated the effects of exogenous nitric oxide (NO) on growth, antioxidant enzymes, and key nitrogen metabolism enzymes in pepper seedlings under high-temperature stress. In addition, targeted metabolomics was used to study the differential accumulation of amino acid metabolites, thereby providing theoretical support for the use of exogenous substances to mitigate high-temperature stress damage in plants. The results showed that high-temperature stress increased soluble sugar, soluble protein, amino acids, proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, electrolyte leakage, and superoxide anion (O2·-) production rate while altering the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX)] and key nitrogen metabolism enzymes [nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), and nitric oxide synthase (NOS)]. c-PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, an NO scavenger) exacerbates oxidative stress and further reduces NO content and enzyme activities. However, exogenous SNP (sodium nitroprusside, an NO donor) effectively alleviated these adverse effects by enhancing antioxidant defense mechanisms, increasing NO content, and normalizing amino acid metabolite levels (kynurenine, N-acetyl-L-tyrosine, L-methionine, urea, and creatine), thereby maintaining normal plant growth. These findings suggest that SNP can enhance stress tolerance in pepper seedlings by improving osmotic regulation, antioxidant capacity, and nitrogen metabolism, effectively mitigating the damage caused by high-temperature stress. [ABSTRACT FROM AUTHOR]

Brazilian soils are predominantly rich in aluminum, which becomes mobile at pH < 5, affecting sensitive plants; however, some species have developed aluminum tolerance mechanisms. The purpose of this study was to compare the physiological responses of Crotalaria genus species, family Fabaceae, which have the ability to associate with nitrogen-fixing bacteria under the influence of Al3+ in the soil. The soil used was Oxisol; the experimental design was in randomized blocks in a factorial scheme (2 × 3): soil factor (available toxic aluminum content; correction of dolomitic limestone—MgCO3) and species factor (C. juncea; C. spectabilis; C. ochroleuca); cultivated within 43, 53, and 53 days, respectively, with five replications; 30 experimental samples. Mass and length, pigments, gas exchange, and changes in nitrogen metabolism were evaluated. C. juncea showed a higher concentration of amino acids in the leaves, internal carbon, and stomatal conductance in soil with Al3+, as well as higher production of ureides, allantoinic acid, allantoic acid, proteins, and amino acids in the nodules, with 78% of the Al3+ accumulation occurring in the roots. C. ochroleuca demonstrated greater shoot length and nodule number production in limed soil; in soil with Al3+, it showed a 91% increase in chlorophyll a content and 93% in carotenoids. C. spectabilis showed a 93% increase in ureide production in the leaves in soil with Al3+. [ABSTRACT FROM AUTHOR]

Boron (B) deficiency has been shown to inhibit root cell growth and division. However, the precise mechanism underlying B deficiency-mediated root tip growth inhibition remains unclear. In this study, we investigated the role of BnaA3.NIP5;1, a gene encoding a boric acid channel, in Brassica napus (B. napus). BnaA3.NIP5;1 is expressed in the lateral root cap and contributes to B acquisition in the root tip. Downregulation of BnaA3.NIP5;1 enhances B sensitivity in B. napus, resulting in reduced shoot biomass and impaired root tip development. Transcriptome analysis was conducted on root tips from wild-type B. napus (QY10) and BnaA3.NIP5;1 RNAi lines to assess the significance of B dynamics in meristematic cells during seedling growth. Differentially expressed genes (DEGs) were significantly enriched in plant circadian rhythm and nitrogen (N) metabolism pathways. Notably, the circadian-rhythm-related gene HY5 exhibited a similar B regulation pattern in Arabidopsis to that observed in B. napus. Furthermore, Arabidopsis mutants with disrupted circadian rhythm (hy5/cor27/toc1) displayed heightened sensitivity to low B compared to the wild type (Col-0). Consistent with expectations, B deficiency significantly disrupted N metabolism in B. napus roots, affecting nitrogen concentration, nitrate reductase enzyme activity, and glutamine synthesis. Interestingly, this disruption was exacerbated in BnaA3NIP5;1 RNAi lines. Overall, our findings highlight the critical role of B dynamics in root tip cells, impacting circadian rhythm and N metabolism, ultimately leading to retarded growth. This study provides novel insights into B regulation in root tip development and overall root growth in B. napus. [ABSTRACT FROM AUTHOR]

The paper presents the experimental study of the influence of a 50 Hz extremely-low-frequency (ELF) electromagnetic field (EMF) on the growth of microalgae Chlorella vulgaris in a BG11 culture medium. Comparative experimental determinations carried out under reference conditions (microalgae growth without exposure to EMF) and with exposure to a homogeneous 50 Hz EMF of various intensities highlighted the fact that EMF has a major impact on both the growth speed and the nitrogen and phosphorus content of the obtained algal mass. Through spectrophotometry and gravimetric determinations, it was found that the lag time was reduced from approximately 8 h (reference) to approximately 6 h for EMF of 2 V/m, 4.5 h for EMF of 5 V/m, 3.2 h for EMF of 10 V/m, and 2.5 h for EMF of 15 V/m. In the stimulation with 15 V/m EMF, the maximum biomass growth rate was 2.75 times higher than the reference, leading to a 2-fold increase in the rate of exhaustion of nutrients, especially phosphorus, in the culture medium. The specific chemical analyses for N-NO3, total nitrogen TNb, and total phosphorus Pt highlighted that the N-NO3 content of the culture medium decreased by 58 mg/L/day at 15 V/m EMF compared to 43 mg/L for the reference. The Pt content decreased to 90% depletion after approximately 80 h for the reference culture medium, versus only 48 h of growth with exposure to 15 V/m ELF. The TNb content of the algal suspension in BG11 under the influence of 15 V/m EMF for 96 h of growth increased 14 times compared to the reference. This shows that nitrogen metabolization in the dispersed air was significantly stimulated. It was also found that the 50 Hz EMF also influences the nitrogen and phosphorus content of the increased algal mass. The results show the potential of EMF stimulation of Chlorella vulgaris growth, leading to an increased efficiency of algae growth reactors. [ABSTRACT FROM AUTHOR]

This study extensively analyzed the bacterial information of biofilms and activated sludge in oxic reactors of full-scale moving bed biofilm reactor-integrated fixed-film activated sludge (MBBR-IFAS) systems. The bacterial communities of biofilms and activated sludge differed statistically (R = 0.624, p < 0.01). The denitrifying genera Ignavibacterium, Phaeodactylibacter, Terrimonas, and Arcobacter were more abundant in activated sludge (p < 0.05), while comammox Nitrospira was more abundant in biofilms (p < 0.05), with an average relative abundance of 8.13%. Nitrospira and Nitrosomonas had weak co-occurrence relationships with other genera in the MBBR-IFAS systems. Potential function analysis revealed no differences in pathways at levels 1 and 2 based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) between biofilms and activated sludge. However, in terms of pathways at level 3, biofilms had more potential in 26 pathways, including various organic biodegradation and membrane and signal transportation pathways. In comparison, activated sludge had more potential in only five pathways, including glycan biosynthesis and metabolism. With respect to nitrogen metabolism, biofilms had greater potential for nitrification (ammonia oxidation) (M00528), and complete nitrification (comammox) (M00804) concretely accounted for methane/ammonia monooxygenase (K10944, K10945, and K10946) and hydroxylamine dehydrogenase (K10535). This study provides a theoretical basis for MBBR-IFAS systems from the perspective of microorganisms. [ABSTRACT FROM AUTHOR]

The rhizospheric microorganisms of agricultural crops play a crucial role in plant growth and nutrient cycling. In this study, we isolated two Streptomyces strains, Streptomyces sp. LM32 and Streptomyces sp. LM65, from the rhizosphere of Vitis vinifera L. We then conducted genomic analysis by assembling, annotating, and inferring phylogenomic information from the whole genome sequences. Streptomyces sp. strain LM32 had a genome size of 8.1 Mb and a GC content of 72.14%, while Streptomyces sp. strain LM65 had a genome size of 7.3 Mb and a GC content of 71%. Through ANI results, as well as phylogenomic, pan-, and core-genome analysis, we found that strain LM32 was closely related to the species S. coelicoflavus, while strain LM65 was closely related to the species S. achromogenes subsp. achromogenes. We annotated the functional categories of genes encoded in both strains, which revealed genes involved in nitrogen and phosphorus metabolism. This suggests that these strains have the potential to enhance nutrient availability in the soil, promoting agricultural sustainability. Additionally, we identified gene clusters associated with nitrate and nitrite ammonification, nitrosative stress, allantoin utilization, ammonia assimilation, denitrifying reductase gene clusters, high-affinity phosphate transporter and control of PHO regulon, polyphosphate, and phosphate metabolism. These findings highlight the ecological roles of these strains in sustainable agriculture, particularly in grapevine and other agricultural crop systems. [ABSTRACT FROM AUTHOR]

Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant–TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers—malondialdehyde and 5-methylcytosine—and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination. [ABSTRACT FROM AUTHOR]

When treating municipal wastewater, nitrogen removal is often limited due to low C/N, which needs to be compensated for by additional carbon source injections. This study investigated the feasibility of using industrial-waste polyglycolic acid (PGA) as a carbon source for denitrification in an SBR to obtain an economical carbon source. The results revealed that an optimal denitrification performance in a methanol-fed activated sludge system was achieved with a PGA dosage of 1.2 mL/L, a pH of 7–8, and a dissolved-oxygen (DO) concentration of 3 ± 0.5 mg/L. Under these conditions, all quality parameters for effluent water met the required criteria [COD < 50 mg/L; TN < 15 mg/L; NH4+-N < 5(8) mg/L]. PGA enhanced the variety and richness of microbial communities, thereby markedly increasing the relative abundance of major phyla such as Proteobacteria and Bacteroidota and major genera such as Paracoccus and Dechloromonas. Furthermore, PGA upregulated the expression of nitrogen-metabolism-related genera, including amo, hao, nar, and nor, which improved the denitrification performance of the system. This study provides a reference for applying PGA as a carbon source for low-C/N-wastewater treatment and solid-waste utilization. [ABSTRACT FROM AUTHOR]

Polyphenol-rich grape pomace (GP) represents a valuable processing by-product with considerable potential as sustainable livestock feed. This study aimed to investigate the effects of different levels of GP on the growth performance and nitrogen utilization efficiency, antioxidant activity, and rumen and rectum microbiota of Angus bulls. Thirty Angus bulls were allocated three dietary treatments according to a completely randomized design: 0% (G0), 10% (G10), and 20% (G20) corn silage dry matter replaced with dried GP dry matter. The results showed that the average daily gain (ADG) of the G0 group and G10 group was higher than that of the G20 group (p < 0.05); urinary nitrogen levels decreased linearly with the addition of GP (linear, p < 0.05). In terms of antioxidants, the levels of catalase (CAT) in the G10 group were higher than in the G0 and G20 groups (p < 0.05), and the total antioxidative capacity (T-AOC) was significantly higher than that in the G20 group (p < 0.05). In addition, in the analysis of a microbial network diagram, the G10 group had better microbial community complexity and stability. Overall, these findings offer valuable insights into the potential benefits of incorporating GP into the diet of ruminants. [ABSTRACT FROM AUTHOR]

To enhance the nutrient removal efficiency of Oocystis borgei for mariculture wastewater (MW), the effects and processes of three phytohormones on nitrogen and phosphorus removal from synthetic mariculture wastewater (SMW) by O. borgei under sequential batch operation were compared. The findings revealed that the supplementation with 10−6 M 3-indoleacetic acid (IAA), gibberellic acid (GA3), and zeatin (ZT) resulted in the most effective elimination, while there was no appreciable difference among them. The nitrogen and phosphorus indices of the effluent dramatically reduced (p < 0.01) upon the supplementation of phytohormones, and the removal effects were ranked as NO3−-N > PO43−-P > NH4+-N > NO2−-N. The removal rates for NH4+-N and PO43−-P were 0.72–0.74 mg·L−1·d−1 and 1.26–1.30 mg·L−1·d−1, respectively. According to physiological studies, phytohormones enhanced the levels of photosynthetic pigments and chlorophyll fluorescence parameters (Fv/Fm and φPSII), thereby improving photosynthetic activity. Additionally, they stimulated Nitrate Reductase (NR) and Glutamine Synthetase (GS) activities to promote nitrogen metabolism and increased Superoxide Dismutase (SOD), Catalase (CAT), and carotenoid contents to mitigate oxidative stress damage caused by abiotic stress. These activities contribute to the proliferation of O. borgei, which in turn resulted in an increase in the assimilation of nitrogen and phosphorus from SMW. In conclusion, phytohormone supplementation significantly increased nutrient removal from SMW by O. borgei in a sequential batch reactor, which has potential application in MW treatment. [ABSTRACT FROM AUTHOR]

Chinese cabbage is the most widely consumed vegetable crop due to its high nutritional value and rock-bottom price. Notably, the presence of the physiological disease petiole spot significantly impacts the appearance quality and marketability of Chinese cabbage. It is well known that excessive nitrogen fertilizer is a crucial factor in the occurrence of petiole spots; however, the mechanism by which excessive nitrogen triggers the formation of petiole spots is not yet clear. In this study, we found that petiole spots initially gather in the intercellular or extracellular regions, then gradually extend into intracellular regions, and finally affect adjacent cells, accompanied by cell death. Transcriptomic and proteomic as well as physiology analyses revealed that the genes/proteins involved in nitrogen metabolism exhibited different expression patterns in resistant and susceptible Chinese cabbage lines. The resistant Chinese cabbage line has high assimilation ability of NH4+, whereas the susceptible one accumulates excessive NH4+, thus inducing a burst of reactive oxygen species (ROS). These results introduce a novel perspective to the investigation of petiole spot induced by the nitrogen metabolism pathway, offering a theoretical foundation for the development of resistant strains in the control of petiole spot. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated the effects of guanidinoacetic acid (GAA) supplementation on the growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism of Angus steers. In a 130-day feeding experiment, steers receiving GAA at a conventional dose (0.8 g/kg) and a high dose (1.6 g/kg) exhibited significantly higher average daily weight gain and improved feed conversion efficiency compared to the control group without GAA. GAA supplementation also influenced rumen fermentation, with lower acetate levels, higher propionate levels, and higher acetate: propionate ratio in GAA groups. Blood analyses revealed elevated concentrations of urea, blood ammonia, GAA, creatine, and catalase, indicating improved creatine metabolism and antioxidant activity. A subsequent 3-day digestive metabolism experiment confirmed that the GAA-supplemented groups had increased dry matter and crude protein digestibility, as well as increased N retention and improved organismal nitrogen metabolism. In summary, dietary GAA supplementation at a 0.8 g/kg and 1.6 g/kg DM basis positively influenced growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism in Angus steers, emphasizing its potential as a nutritional strategy. Guanidinoacetic acid (GAA) functions as a precursor for creatine synthesis in the animal body, and maintaining ample creatine reserves is essential for fostering rapid growth. This study aimed to explore the impact of GAA supplementation on growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism in Angus steers through two experiments: a feeding experiment (Experiment 1) and a digestive metabolism experiment (Experiment 2). In Experiment 1, thirty-six Angus steers (485.64 ± 39.41 kg of BW) at 16 months of age were randomly assigned to three groups: control (CON), a conventional dose of GAA (CGAA, 0.8 g/kg), and a high dose of GAA (HGAA, 1.6 g/kg), each with twelve steers. The adaptation period lasted 14 days, and the test period was 130 days. Weighing occurred before morning feeding on days 0, 65, and 130, with rumen fluid and blood collected before morning feeding on day 130. Experiment 2 involved fifteen 18-month-old Angus steers (575.60 ± 7.78 kg of BW) randomly assigned to the same three groups as in Experiment 1, with a 7-day adaptation period and a 3-day test period. Fecal and urine samples were collected from all steers during this period. Results showed a significantly higher average daily gain (ADG) in the CGAA and HGAA groups compared to the CON group (p = 0.043). Additionally, the feed conversion efficiency (FCE) was significantly higher in the CGAA and HGAA groups than in the CON group (p = 0.018). The concentrations of acetate and the acetate:propionate ratio were significantly lower in the CGAA and HGAA groups, while propionate concentration was significantly higher (p < 0.01). Serum concentration of urea (UREA), blood ammonia (BA), GAA, creatine, and catalase (CAT) in the CGAA and HGAA groups were significantly higher than in the CON group, whereas malondialdehyde (MDA) concentrations were significantly lower (p < 0.05). Digestibility of dry matter (DM) and crude protein (CP) and the nitrogen retention ratio were significantly higher in the CGAA and HGAA groups than in the CON group (p < 0.05). In conclusion, dietary addition of both 0.8 g/kg and 1.6 g/kg of GAA increased growth performance, regulated rumen fermentation and blood indices, and improved digestibility and nitrogen metabolism in Angus steers. However, higher doses of GAA did not demonstrate a linear stacking effect. [ABSTRACT FROM AUTHOR]

Optimal plant growth in many species is achieved when the two major forms of N are supplied at a particular ratio. This study investigated optimal nitrogen forms and ratios for tomato growth using the 'Jingfan 502' tomato variety. Thirteen treatments were applied with varying proportions of nitrate nitrogen (NN), ammonium nitrogen (AN), and urea nitrogen (UN). Results revealed that the combination of AN and UN inhibited tomato growth and photosynthetic capacity. Conversely, the joint application of NN and UN or NN and AN led to a significant enhancement in tomato plant growth. Notably, the T12 (75%UN:25%NN) and T4 (75%NN:25%AN) treatments significantly increased the gas exchange and chlorophyll fluorescence parameters, thereby promoting the accumulation of photosynthetic products. The contents of fructose, glucose, and sucrose were significantly increased by 121.07%, 206.26%, and 94.64% and by 104.39%, 156.42%, and 61.40%, respectively, compared with those in the control. Additionally, AN favored starch accumulation, while NN and UN favored fructose, sucrose, and glucose accumulation. Gene expression related to nitrogen and sugar metabolism increased significantly in T12 and T4, with T12 showing greater upregulation. Key enzyme activity in metabolism also increased notably. In summary, T12 enhanced tomato growth by upregulating gene expression, increasing enzyme activity, and boosting photosynthesis and sugar accumulation. Growers should consider using NN and UN to reduce AN application in tomato fertilization. [ABSTRACT FROM AUTHOR]

Actinobacteria from the genus Streptomyces feature complex primary and secondary metabolism, developmental cycle, and ability to produce a variety of natural products. These soil bacteria are major producers of antibiotics and other bioactive compounds and have been extensively investigated due to the medical and industrial relevance of Streptomyces-derived secondary metabolites. However, the genetic toolbox for Streptomyces engineering as well as yield optimization strategies for the production of relevant metabolites are limited. On the one hand, the genetic potential of these organisms has not been fully utilized due to many "silent" or poorly expressed biosynthetic gene clusters, whose activation depends on environmental stimuli and nutrient availability. On the other hand, these GC-rich Gram-positive bacteria are difficult to manipulate, and traditional genetic manipulation strategies are time-consuming and have low efficiency. Recent studies of Streptomyces metabolism and genomes provided new insights into possibilities to overcome these challenges. In this review, advances and approaches for Streptomyces manipulations and secondary metabolite production optimization are discussed. Special focus is given to understanding the interplay between primary and secondary metabolism in Streptomyces and the supply of nitrogen-containing compounds into secondary metabolism. Existing strategies to manipulate cellular metabolism in Streptomyces are reviewed. [ABSTRACT FROM AUTHOR]

The root-colonizing endophytic fungus Piriformospora indica promotes the root and shoot growth of its host plants. We show that the growth promotion of Arabidopsis thaliana leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote 15NO3− uptake from agar plates to the leaves of the host under N-sufficient or N-limiting conditions. However, when the roots were co-cultivated with 15N-labelled P. indica, more labels were detected in the leaves of N-starved host plants but not in plants supplied with sufficient N. Amino acid and primary metabolite profiles, as well as the expression analyses of N metabolite transporter genes suggest that the fungus alleviates the adaptation of its host from the N limitation condition. P. indica alters the expression of transporter genes, which participate in the relocation of NO3−, NH4+ and N metabolites from the roots to the leaves under N limitation. We propose that P. indica participates in the plant's metabolomic adaptation against N limitation by delivering reduced N metabolites to the host, thus alleviating metabolic N starvation responses and reprogramming the expression of N metabolism-related genes. [ABSTRACT FROM AUTHOR]

Simple Summary: Dietary methionine deficiency can limit the body growth and cashmere production of cashmere goats, leading to excessive nitrogen (N) excretion. This study demonstrated that rumen-protected methionine supplementation improved the growth performance of cashmere goats and reduced their manure N excretions and plasma urea N levels during the seasonal growth of cashmere fibres. The formulation of diets supplemented with rumen-protected methionine can enhance the utilisation of N and maximise the production capacity of cashmere goats. This study determined the effects of rumen-protected methionine (RPM) supplementation on the growth performance, nutrient digestibility, nitrogen (N) utilisation and plasma amino acid profiles of Liaoning cashmere goats during cashmere fibre growth. Twenty-four yearling male cashmere goats (body weight: 35.41 ± 1.13 kg) were randomly assigned to four dietary treatments: a corn–soybean meal basal diet deficient in methionine (negative control, NC) and a basal diet supplemented with 1, 2 and 3 g/kg of RPM. The RPM supplementation quadratically increased the average daily gain (ADG) and decreased the feed to gain ratio (p = 0.001) without affecting the final body weight and dry matter intake. In particular, compared to NC, 2 g/kg RPM supplementation increased the ADG by 35 g/d (p < 0.001) and resulted in the lowest feed to gain ratio (p < 0.001). RPM increased the apparent total tract digestibility of N and decreased the faecal N levels, both in a linear fashion (p = 0.005). Urinary N levels did not have an effect, but the N retention levels increased linearly with PRM (p = 0.032). Moreover, the RPM decreased the plasma urea N levels (p < 0.001) and increased the plasma Met levels quadratically (p < 0.001). In conclusion, RPM supplementation in the diet of cashmere goats can enhance the utilisation of N and improve ADG during the cashmere fibre growing period, and 2 g/kg of RPM in the diet is suggested. [ABSTRACT FROM AUTHOR]

Plants uptake and assimilate nitrogen from the soil in the form of nitrate, ammonium ions, and available amino acids from organic sources. Plant nitrate and ammonium transporters are responsible for nitrate and ammonium translocation from the soil into the roots. The unique structure of these transporters determines the specificity of each transporter, and structural analyses reveal the mechanisms by which these transporters function. Following absorption, the nitrogen metabolism pathway incorporates the nitrogen into organic compounds via glutamine synthetase and glutamate synthase that convert ammonium ions into glutamine and glutamate. Different isoforms of glutamine synthetase and glutamate synthase exist, enabling plants to fine-tune nitrogen metabolism based on environmental cues. Under stressful conditions, nitric oxide has been found to enhance plant survival under drought stress. Furthermore, the interaction between salinity stress and nitrogen availability in plants has been studied, with nitric oxide identified as a potential mediator of responses to salt stress. Conversely, excessive use of nitrate fertilizers can lead to health and environmental issues. Therefore, alternative strategies, such as establishing nitrogen fixation in plants through diazotrophic microbiota, have been explored to reduce reliance on synthetic fertilizers. Ultimately, genomics can identify new genes related to nitrogen fixation, which could be harnessed to improve plant productivity. [ABSTRACT FROM AUTHOR]

Glufosinate is a broad-spectrum herbicide used to control most weeds in agriculture worldwide. Goosegrass (Eleusine indica L.) is one of the top ten malignant weeds across the world, showing high tolerance to glufosinate via different mechanisms that are not yet fully understood. This study revealed that nitrogen metabolism could be a target-resistant site, providing clues to finally clarify the mechanism of glufosinate resistance in resistant goosegrass populations. Compared to susceptible goosegrass (NX), the resistant goosegrass (AUS and CS) regarding the stress of glufosinate showed stronger resistance with lower ammonia contents, higher target enzyme GS (glutamine synthetase) activity, and lower GOGAT (glutamine 2-oxoglutarate aminotransferase) activity. The GDH (glutamate dehydrogenase) activity of another pathway increased, but its gene expression was downregulated in resistant goosegrass (AUS). Analyzing the transcriptome and proteome data of goosegrass under glufosinate stress at 36 h showed that the KEGG pathway of the nitrogen metabolism was enriched in glufosinate-susceptible goosegrass (NX), but not in glufosinate-resistant goosegrass (CS and AUS). Several putative target genes involved in glufosinate stress countermeasures were identified. This study provides specific insights into the nitrogen metabolism of resistant goosegrass, and gives a basis for future functional verification of glufosinate-tolerance genes in plants. [ABSTRACT FROM AUTHOR]

Edible halophyte Portulaca oleracea L., known as purslane, was grown in two percentages of artificial seawater (ASW) under two combined red (R) and blue (B) LED spectra. High salinity (40% ASW) negatively affected shoot productivity and leaf growth of purslane compared to those grown in 10% ASW. Photosynthetic pigment and total reduced nitrogen concentrations were significantly higher in purslane grown in 10% ASW than in 40% ASW. However, LED spectral quality did not markedly influence these parameters. Grown in 10% ASW under R/B 2.2, purslane had the highest maximum nitrate reductase activity, while those in 40% ASW under R/B 2.2 had the highest activation state. Under both light qualities, purslane had a sevenfold increase in proline concentration in 40% ASW than in 10% ASW. Total phenolic compounds' concentration was the highest in 10% ASW under R/B 0.9, while there were no significant differences in the accumulation of total soluble sugars and ascorbic acids among all plants. Antioxidant enzymes activities were lower in 40% ASW under R/B 2.2 compared to the other conditions. In conclusion, salinity affected the yield, physiology and nutritional quality of purslane. The impacts of LED spectral quality on purslane were only reflected by certain physiological and nutritional parameters. [ABSTRACT FROM AUTHOR]

Field experiments were conducted to investigate the effects of K application on the nitrogen and potassium utilization efficiency and yield of foxtail millet (Setaria italica L.). The experiment was performed with a completely randomized design with two millet cultivars (Jingu 21 and Zhangza 10) and five K2O rates (0, 60, 120, 180, and 240 kg/hm2) in 2020 and 2021. We found that K promoted K and N absorption; significantly increased dry matter (DM), N, and K accumulation in millet organs; caused dry matter accumulation to peak earlier; and increased the DM accumulation rate. In addition, K accumulation preceded that of DM or N. Relative to the crop cycle, most K (61.07%) accumulated at booting, whereas N accumulated mostly (33.86%) during grain filling. N absorption efficiency increased by 31.87%, and the apparent and agronomic utilization rate of K fertilizer remained high, increasing millet yield, which peaked at a K rate of 180 kg/hm2 for both cultivars, by 29.91% and 31.51% in Jingu 21 and Zhangza 10, respectively, relative to untreated controls. Stepwise regression and path analysis showed that the leaf and spike K accumulation, stem N accumulation, and stem DM were the main factors affecting yield, with DM having the greatest direct effect, followed by leaf K accumulation. The K concentration (0.77–3.04%) in Zhangza 10 was higher than that in Jingu 21 (0.69–2.91%) in untreated plants. Under the same K application rate, N and K accumulation and the harvest index were higher for Zhangza 10 than those for Jingu 21, and the nutrient utilization ability was greater for Zhangza 10. The results demonstrated that rational K fertilizer application can increase K concentration and accumulation in leaves, promote N metabolism and accumulation, increase N and K utilization efficiency, and improve DM accumulation and millet yield. [ABSTRACT FROM AUTHOR]

The influence of drought induced by polyethylene glycol (PEG) and the alleviatory effect of nitric oxide (50 µM) and sulphur (S, 1 mM K2SO4) were studied in Vigna radiata. Drought stress reduced plant height, dry weight, total chlorophylls, carotenoids and the content of nitrogen, phosphorous, potassium and sulphur. The foliar applications of NO and sulphur each individually alleviated the decline, with a greater alleviation observed in seedlings treated with both NO and sulphur. The reduction in intermediates of chlorophyll synthesis pathways and photosynthesis were alleviated by NO and sulphur. Oxidative stress was evident through the increased hydrogen peroxide, superoxide and activity of lipoxygenase and protease which were significantly assuaged by NO, sulphur and NO + sulphur treatments. A reduction in the activity of nitrate reductase, glutamine synthetase and glutamate synthase was mitigated due to the application of NO and the supplementation of sulphur. The endogenous concentration of NO and hydrogen sulphide (HS) was increased due to PEG; however, the PEG-induced increase in NO and HS was lowered due to NO and sulphur. Furthermore, NO and sulphur treatments to PEG-stressed seedlings further enhanced the functioning of the antioxidant system, osmolytes and secondary metabolite accumulation. Activities of γ-glutamyl kinase and phenylalanine ammonia lyase were up-regulated due to NO and S treatments. The treatment of NO and S regulated the expression of the Cu/ZnSOD, POD, CAT, RLP, HSP70 and LEA genes significantly under normal and drought stress. The present study advocates for the beneficial use of NO and sulphur in the mitigation of drought-induced alterations in the metabolism of Vigna radiata. [ABSTRACT FROM AUTHOR]

Algae extract biostimulants increase nutrient uptake, stress tolerance, and productivity in several crops. However, there is still a gap in the knowledge of the mechanisms of action of algae extracts on nitrogen plant metabolism. This study aimed to evaluate the effect of a commercial Ascophyllum nodosum algae extract on nitrogen metabolism in nodulating soybean plants and their productivity. Two concentrations of algae extract (0.25% and 0.50%) were used, which were applied via seeds and leaf spray. Seeds were treated at sowing, and plants were sprayed twice at two vegetative phenological stages. Plants were harvested at the R5 phenological stage for leaf biochemical and enzyme activity analyses and leaf and root gene expression analyses. The experiment was carried out a second time to evaluate productivity. There was an increase in leaf and stem biomass, number of pods and seeds, weight of pods and seeds, and productivity in plants treated with both concentrations. Biochemical analysis showed increased amino acid content in leaves after extract application. No marked differences were found regarding the parameters related to nitrogen metabolism when the data were analysed individually. However, principal component analysis and gene expression heatmaps supported the conclusion that N metabolism was affected by algae extract application, leading to higher seed production. [ABSTRACT FROM AUTHOR]

Stropharia rugosoannulata has been used in environmental engineering to degrade straw in China. The nitrogen and carbon metabolisms are the most important factors affecting mushroom growth, and the aim of this study was to understand the effects of different nitrogen levels on carbon metabolism in S. rugosoannulata using transcriptome analysis. The mycelia were highly branched and elongated rapidly in A3 (1.37% nitrogen). GO and KEGG enrichment analyses revealed that the differentially expressed genes (DEGs) were mainly involved in starch and sucrose metabolism; nitrogen metabolism; glycine, serine and threonine metabolism; the MAPK signaling pathway; hydrolase activity on glycosyl bonds; and hemicellulose metabolic processes. The activities of nitrogen metabolic enzymes were highest in A1 (0.39% nitrogen) during the three nitrogen levels (A1, A2 and A3). However, the activities of cellulose enzymes were highest in A3, while the hemicellulase xylanase activity was highest in A1. The DEGs associated with CAZymes, starch and sucrose metabolism and the MAPK signaling pathway were also most highly expressed in A3. These results suggested that increased nitrogen levels can upregulate carbon metabolism in S. rugosoannulata. This study could increase knowledge of the lignocellulose bioconversion pathways and improve biodegradation efficiency in Basidiomycetes. [ABSTRACT FROM AUTHOR]

Simple Summary: Colon cancer is one of the common cancers affecting a large number of patients globally. In sporadic CRC, several genetic factors may play important roles such as genetic mutations, genetic instability, and DNA promoter methylation. However, the role of inflammatory pathogenesis of sporadic CRC is less widely appreciated. Ulcerative colitis (UC) provides a unique opportunity to identify genes dysregulated in colon inflammation in human subjects and to exploit those pathways as a proxy of inflammation. In this study, we identified a number of such dysregulated metabolic and other pathways in UC and demonstrated that many of those inflammation-related gene pathways were also associated with sporadic CRC. The findings from US patients were also replicated in Bangladeshi patients with CRC. We demonstrate that this "inflammation—cancer" association was independent of sex and conventional genetic factors. The study widens our understanding of CRC pathogenesis and some of these dysregulated pathways may provide useful therapeutic options in the future. The association of chronic inflammation with colorectal carcinoma (CRC) development is well known in ulcerative colitis (UC). However, the role of inflammatory changes in sporadic CRC pathogenesis is less widely appreciated. In this study, in the first step using RNA-seq, we identified gene-pathway-level changes in UC-associated CRC (UC CRC, n = 10) and used the changes as a proxy for inflammation in human colon to ask if there were associations of inflammatory pathway dysregulations in sporadic CRC pathogenesis (n = 8). We found down-regulations of several inflammation-related metabolic pathways (nitrogen metabolism, sulfur metabolism) and other pathways (bile secretion, fatty acid degradation) in sporadic CRC. Non-inflammation-related changes included up-regulation of the proteasome pathway. In the next step, from a larger number of paired samples from sporadic CRC patients (n = 71) from a geographically and ethnically different population and using a different platform (microarray), we asked if the inflammation-CRC association could be replicated. The associations were significant even after stratification by sex, tumor stage, grade, MSI status, and KRAS mutation status. Our findings have important implications to widen our understanding of inflammatory pathogenesis of sporadic CRC. Furthermore, targeting of several of these dysregulated pathways could provide the basis for improved therapies for CRC. [ABSTRACT FROM AUTHOR]

The input of large amounts of fertilizers in agricultural areas may result in nitrogen (N) leakage to nearby forest fragments, which can impact the physiology and growth of trees. The current study aimed to assess the effects of soil N addition on seedlings of four tree species in the Brazilian Atlantic Forest: Croton floribundus and Astronium graveolens (pioneer), Guarea kunthiana and Aspidosperma polyneuron (non-pioneer). The experiment was carried out in a greenhouse condition with three treatments: reference (soil without addition of nutrients), N addition (N: soil with addition of ammoniacal-N), and complete (C: soil with addition of ammoniacal-N and other macro and micronutrients). Croton floribundus seedlings presented higher shoot growth with N addition, mainly in treatment C, and only this treatment increased net photosynthesis. There was great variation in the metabolic responses induced by treatments N and C, with accumulation of nitrate in the leaves and xylem sap only in seedlings in treatment N. In A. graveolens, there was a decrease in transpiration in response to treatments N and C. However, water use efficiency, leaf area, and dry mass increased only in seedlings subjected to treatment C. Regarding metabolic parameters, A. graveolens was little responsive to the treatments. In G. kunthiana seedlings, the treatments decreased net photosynthesis and increased leaf total N. Only treatment N led to decreased stem dry mass and increased nitrate contents in leaves and xylem sap. Aspidosperma polyneuron exhibited no change in growth, but there was an accumulation of N compounds in the leaves for both treatments N and C, which suggests that this species could be a good bioindicator of N addition to the soil. Although influencing different parameters, the results indicate that soil N addition affects the performance of both pioneer and non-pioneer species. Finally, the implications of these results for biomonitoring of N availability in the soil of forest fragments are discussed. [ABSTRACT FROM AUTHOR]

Low temperature is the main factor for global natural disasters affecting the growth and distribution of plants, and cotton may be affected by low temperature and cold damage at all growth stages. In addition, the insecticidal resistance of cultivars has been reported to perform poorly or unstably due to adverse environments. The present study aimed to investigate the impact of low temperature on the levels of insecticidal protein in Bacillus thuringiensis (Bt) transgenic cotton plants during the peak boll stage. To achieve this, two Bt cotton cultivars, Sikang1 (SK1) and Sikang3 (SK3), were subjected to different temperature regimes and durations. The findings of the study demonstrated that the expression of insecticidal protein in the boll shell of Bt transgenic cotton plants was significantly inhibited under low-temperature stress. Specifically, in 2020, compared to the CK (27 °C), the insecticidal protein content in the boll shell of SK3 decreased by 28.19% after a 48 h of a 16 °C temperature. These results suggest that low-temperature stress can negatively impact the expression of insecticidal protein in Bt transgenic cotton, highlighting the need for appropriate measures to minimize its adverse effects on cotton production. In addition, the threshold temperature that leads to a significant decrease in the content of insecticidal proteins symbolizes an upward trend as the duration of stress prolongs. Decreased Bt protein content at low temperatures is associated with changes in the N metabolism. The present study revealed a significant positive correlation between the levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) activities, as well as in the soluble protein levels in the boll shell and the content of the Bt protein. On the other hand, a significant negative correlation was observed between the levels of free amino acids, peptidase, and protease activities, as well as of Bt protein content. These findings suggest that, in Bt cotton production, it is crucial to remain vigilant of prolonged low-temperature disasters, which last for over 12 h and drop below 17–20 °C during the peak boll stage. Such conditions may reduce insecticidal resistance, leading to substantial economic losses. [ABSTRACT FROM AUTHOR]

The beneficial role of glycine betaine (GB) in the adaptation of plants to abiotic stresses is well known; therefore, the study of physiological and molecular responses induced by exogenous GB under NaCl stress can provide a suitable reference for the application of this compound to enhance the adaptation of plants to salinity. The present study was conducted under in vitro conditions to evaluate the effect of GB (25 and 50 mM) on the growth, physiological, and molecular traits of Stevia rebaudiana during NaCl toxicity (50 mM). The results showed that applying NaCl treatment increased Na accumulation, induced oxidative stress, and disrupted N metabolism and K/Na homeostasis, which, as a result, decreased the stevia plant's growth and biomass. However, application of GB improved the adaptation of NaCl-stressed plants by improving N metabolism and modulating the metabolism of polyamines. By increasing the activity of antioxidant enzymes, GB diminished oxidative stress, protected the plasma membrane, and restored photosynthetic pigments under NaCl toxicity. By reducing Na accumulation and increasing K accumulation, GB maintained the K/Na balance and reduced the effects of toxicity caused by the high Na concentration in stevia leaves. GB increased the leaf accumulation of rebaudioside A in NaCl-stressed plants by modulating the expression of genes (KAH, UGT74G1, UGT76G1, and UGT85C2) involved in the sugar compounds of the stevia plants. Our results provide a broad understanding of GB-induced responses in NaCl-stressed plants, which can help increase our knowledge of the role of GB in the defense mechanisms of plants under abiotic stresses. [ABSTRACT FROM AUTHOR]

Planktonic cells are a vital part of biogeochemical nutrient cycling and play an extremely important role in maintaining the balance of water ecosystems. In this study, surface water samples were collected in three seasons (spring, summer, and winter) 10 km along the estuary of the Bailang River to assess the relationship between environmental factors and the bacterial community structure, which was determined by high-throughput sequencing. The physicochemical properties of the samples, including the pH, salinity, and inorganic nitrogen (NH4+, NO3−, and NO2−), exhibited significant seasonal variations, and the diversity and structure of the bacterial community also varied seasonally. A redundancy analysis showed that the inorganic nitrogen (NH4+, NO3−, NO2−), pH, and salinity are key factors in shaping the bacterial community composition. Among the different seasons, the core taxa of bacterial communities were the same, and Actinobacteria, Cyanobacteria, and Proteobacteria were the key components during the three seasons. The bacterial diversity and structure also varied seasonally, but there were no significant differences in spatial composition. Based on a phylogenetic investigation of communities by reconstruction of unobserved states analysis, nitrogen-cycle-related processes include four dominant processes: nitrogen mineralization, nitrogen fixation, dissimilatory nitrate reduction, and denitrification. These results suggest that the bacterial community structure in the waters of the Bailang River estuary is subject to seasonal rather than spatial variation. These findings provide new evidence for studies of the seasonal variation of bacterial communities in estuaries. [ABSTRACT FROM AUTHOR]

Simple Summary: Excessive protein intake causes dietary nitrogen to be excreted through urine nitrogen and fecal nitrogen, reducing nitrogen use efficiency. The main way to reduce dietary nitrogen loss is to reduce dietary protein content, as well as to meet the nutritional needs of ruminants. Therefore, reducing crude proteins while adding rumen amino acids can achieve a reduction in nitrogen emissions. The results showed that adding RPLys (55 g/d) and RPMet (9 g/d) to the bull diet and low protein diet (11%) could improve the growth performance, increase the level of nitrogen metabolism, and enhance the expression of genes related to nitrogen metabolism. The aim of this study was to investigate the effect of low-protein diets supplemented with rumen-protected lysine (RPLys) and methionine (RPMet) on growth performance, rumen fermentation, blood biochemical parameters, nitrogen metabolism, and gene expression related to N metabolism in the liver of Holstein bulls. Thirty-six healthy and disease-free Holstein bulls with a similar body weight (BW) (424 ± 15 kg, 13 months old) were selected. According to their BW, they were randomly divided into three groups with 12 bulls in each group in a completely randomized design. The control group (D1) was fed with a high-protein basal diet (CP13%), while bulls in two low-protein groups were supplied a diet with 11% crude protein and RPLys 34 g/d·head + RPMet 2 g/d·head (low protein with low RPAA, T2) or RPLys 55 g/d·head + RPMet 9 g/d·head (low protein with high RPAA, T3). At the end of the experiment, the feces and urine of dairy bulls were collected for three consecutive days. Blood and rumen fluid were collected before morning feeding, and liver samples were collected after slaughtering. The results showed that the average daily gain (ADG) of bulls in the T3 group was higher than those in D1 (p < 0.05). Compared with D1, a significantly higher nitrogen utilization rate (p < 0.05) and serum IGF-1 content (p < 0.05) were observed in both T2 and T3 groups; however, blood urea nitrogen (BUN) content was significantly lower in the T2 and T3 groups (p < 0.05). The content of acetic acid in the rumen of the T3 group was significantly higher than that of the D1 group. No significant differences were observed among the different groups (p > 0.05) in relation to the alpha diversity. Compared with D1, the relative abundance of Christensenellaceae_R-7_group in T3 was higher (p < 0.05), while that of Prevotellaceae _YAB2003_group and Succinivibrio were lower (p < 0.05). Compared with D1 and T2 group, the T3 group showed an expression of messenger ribonucleic acid (mRNA) that is associated with (CPS-1, ASS1, OTC, ARG) and (N-AGS, S6K1, eIF4B, mTORC1) in liver; moreover, the T3 group was significantly enhanced (p < 0.05). Overall, our results indicated that low dietary protein (11%) levels added with RPAA (RPLys 55 g/d +RPMet 9 g/d) can benefit the growth performance of Holstein bulls by reducing nitrogen excretion and enhancing nitrogen efficiency in the liver. [ABSTRACT FROM AUTHOR]

Nitrogen loss after urea application and the low nitrogen utilization rate of plants are major issues in fertilizer application. We therefore adopted a combination of urea and 3,4-dimethylpyrazole phosphate (DMPP) applications in order to investigate the response of DMPP in 'sweet sapphire' (V. vinifera L.) grape seedlings growth. Three combinations of DMPP and urea were tested to screen suitable DMPP application concentrations for grape seedlings' growth. Transcriptome differential expression analysis was adopted to elucidate the regulation mechanism of DMPP. The results showed that the application of DMPP with urea significantly increased grape seedlings' root dry weight, as well as the above-ground dry weight. The application of DMPP with urea significantly improved the total root length, surface area, volume, and root vigor. The application of urea nitrogen content with 1% of DMPP (T2) showed optimum effects. The application of DMPP can also significantly increase the net photosynthetic rate, photosynthetic pigments, and fluorescence intensity of grape leaves. Furthermore, the transcriptome differential expression analysis under T2 treatment revealed that members of the Nar (7) and NRT (12) gene families were up-regulated, which promotes nitrogen uptake and metabolism. Moreover, the LHC (11), Psa (7), Pet (4), and Psb (5) genes were up-regulated, which promotes photosynthesis. [ABSTRACT FROM AUTHOR]

GPI-anchored proteins display very diverse biological (biochemical and immunological) functions. An in silico analysis has revealed that the genome of Aspergillus fumigatus contains 86 genes coding for putative GPI-anchored proteins (GPI-APs). Past research has demonstrated the involvement of GPI-APs in cell wall remodeling, virulence, and adhesion. We analyzed a new GPI-anchored protein called SwgA. We showed that this protein is mainly present in the Clavati of Aspergillus and is absent from yeasts and other molds. The protein, localized in the membrane of A. fumigatus, is involved in germination, growth, and morphogenesis, and is associated with nitrogen metabolism and thermosensitivity. swgA is controlled by the nitrogen regulator AreA. This current study indicates that GPI-APs have more general functions in fungal metabolism than cell wall biosynthesis. [ABSTRACT FROM AUTHOR]

Nitrate accumulation is a major factor for the secondary salinization of greenhouse soil in China. Our previous study pointed out that a low ratio of red:far-red light (R:FR) can improve salt tolerance in pakchoi under excessive nitrate stress. However, the nitrogen metabolism mechanism is still unclear. To detect the effect of a low R:FR ratio on nitrogen metabolism of pakchoi under excessive nitrate stress, two extra additions of nitrogen of 80 mmol·L−1 NO3− (H80) and 160 mmol·L−1 NO3− (H160) with/without a low R:FR ratio (R:FR = 0.7) were set, and the growth index, chlorophyll content, key enzymes in nitrogen metabolism, nitrate and glutamic acid content and NRT gene expression level of pakchoi leaves were examined. The results indicated that a low ratio of R:FR could alleviate the reduction in growth and chlorophyll content in pakchoi under high-level nitrogen stress (H80 and H160). The activity of nitrate reductase (NR), glutamine synthetase (GS) and glutamine synthetase (GOGAT) decreased under H80 and H160 conditions, except of NR with the H80 treatment. The activity of glutamate dehydrogenase (GDH) increased under H80 treatment, but decreased under H160 treatment. However, the activity of GDH decreased further by reducing the ratio of R:FR. Excessive nitrate stress increased the nitrate content, and a low R:FR ratio could inhibit nitrate accumulation. However, the change in glutamic acid content was significantly increased under a low R:FR ratio without stress. Under the high-nitrogen level treatment (H160), the use of a low ratio of R:FR increased NRT gene expression. Therefore, a low R:FR ratio (R:FR = 0.7) could effectively promote the growth of pakchoi and improve its nitrogen metabolism, thus alleviating the stress effect of a high level of nitrogen in pakchoi. [ABSTRACT FROM AUTHOR]

The super hybrid rice breeding program in China has raised genetic yield ceilings through morphological improvements and inter-subspecific heterosis. Despite this, little information on the physiological basis underlying this yield transformation exists, and less so on the genotype x environment x management conditions enabling consistent yield gains. Here, we assess grain yield, photosynthetic physiology, and leaf carbon and nitrogen (N) metabolic properties of super rice (Y-liangyou900) under four management practices (i.e., zero-fertilizer control, CK; farmers' practice, FP; high-yield and high-efficiency management, OPT1; and super-high-yield management, OPT2) using a field experiment conducted over five years. Grain yield and agronomic N use efficiency (AEN) of OPT2 were 15% and 10% higher than OPT1, and 30% and 78% higher than FP, respectively. The superior yields of OPT2 were attributed to higher source production capacity, that is, higher leaf photosynthetic rate, carbon metabolic enzyme activity (i.e., AGP and SPS), nitrogen metabolic enzyme activity (i.e., NR, GS, and GOGAT), soluble protein and sugar content, and delayed leaf senescence (the latter due to elevated activity of protective enzyme systems) during grain filling. The higher AEN of OPT2 was associated with higher activity of leaf carbon metabolic enzyme (i.e., AGP and SPS), nitrogen metabolic enzyme (i.e., NR, GS, GDH, and GOGAT) and protective enzyme (POD) after heading, and lower C/N ratio in grains. We conclude that optimized management (optimized water and fertilizer management with appropriate dense planting) improved grain yield and N use efficiency simultaneously by enhancing post-heading leaf carbon and N metabolism and delayed leaf senescence. [ABSTRACT FROM AUTHOR]

Mining valuable genes is helpful to breed high-quality Salvia miltiorrhiza exhibiting efficient nitrogen fertilizer utilization efficiency. In the present study, transcriptome sequencing was introduced to select the candidate transcription factors (TFs) involved in tanshinones' (TAs) and phenolic acids' (PHAs) biosynthesis as well as low nitrogen (LN) stress. In totally, 97.71 Gb clean data was obtained from fifteen sequencing samples and 30,975 unigenes were assembled. Among of them, 27,843 unigenes were successfully annotated. Overall, 8663 differential expression genes (DEGs) were identified, among of which 5034 unigenes were up-regulated, and 3629 unigenes were down-regulated. By enrichment of DEGs together with gene co-expression network construction, 10 candidate TFs including HSFB2b , LBD12 , ERF1A , ERF98 , LBD25 , HSF24 , RAM1 , HSFA4B , TCP8 , and WRKY24 were finally retrieved, which are predicted to participate in modulating TA and PHA biosynthesis under LN stress. Quantitative real-time polymerase chain reaction (qRT-PCR) detection was introduced to further detect the expression profile of candidate TFs under LN stress. These findings offer a valuable resource for in-depth study of TAs 'and PHAs' biosynthesis under LN stress in S. miltiorrhiza .

Nitrogen (N) is the most important fertilizer for increasing crop production, as it is absorbed by various N transporters and metabolized by a series of enzymes. Aspartate aminotransferase (ASP) facilitates the conversion of Glu to Asp for N storage. Chinese cabbage is a typical leafy vegetable that requires a large amount of N for growth. To investigate the functions of BraASPs , 10 members of the ASP gene family in Brassica rapa ( B. rapa ) were identified. Phylogenetic analysis and collinearity comparisons of ASP members among B. rapa , Arabidopsis thaliana ( A. thaliana ), Oryza sativa ( O. sativa ), Brassica napus ( B. napus ), and Brassica oleracea ( B. oleracea ) were conducted to examine evolutionary associations and genome duplication events across species. Multiple cis-acting elements associated with stress responses were identified in the promoters of BraASPs , suggesting their diverse roles. Members of BraASPs were expressed in roots, stems, flowers, siliques, and leaves, with the highest expression in leaves. Their expression levels increased rapidly at 3 h under low N conditions, peaked at 6 h, and returned to low levels at 24 h. Based on transcriptomic data, BraASP1b was identified as a candidate gene in B. rapa under low N stress, localized in the nucleus and cytoplasm. Overexpression of BraASP1b in A. thaliana resulted in a higher biomass than Col-0 under low N conditions.

Background/Objectives: Waxy corn has a unique taste and flavor that a majority of consumers love, and the market application prospect is broad. Nitrogen plays an important role in the growth and development of waxy corn. Exploring the key genes that affect nitrogen absorption can lay a foundation for improving the quality of waxy corn. Methods: In this study, a total of 534 local waxy corn inbred lines were used to perform genome-wide association studies (GWAS) to mine the significant Quantitative Trait Nucleotides (QTNs) for nitrogen content of waxy corn at seedling stage in two different environments. The Weighted Gene Co-Expression Network Analysis (WGCNA) nitrogen response co-expression network was also constructed to explore the differences of gene expression patterns and the co-expression relationship between transcription factors and functional genes to find candidate genes significantly associated with nitrogen uptake in waxy corn. Results: A total of 97 significant associations (LOD-value ≥ 3) were detected between SNPs and nitrate content traits under single and multi-environment conditions. Fifty-four candidate genes were identified around the significant SNPs in about a 20 Kb region. Combined with nitrogen response differential co-expression network analysis, 17 out of the 54 candidate genes were identified in the nitrogen response module, among which 4 main genes ( Zm00001d029012 , Zm00001d034035 , Zm00001d007890 , and Zm00001d045097 ) were repeatedly detected in multiple environments. Conclusions: This study jointly identified four stable and heritable candidate genes involved in the nitrogen metabolism process through GWAS and co-expression network analysis. The results of this study provide theoretical guidance for further elucidating the genetic mechanism of nitrogen efficiency in waxy corn and breeding new germplasm of waxy corn.

Legumes play a pivotal role in addressing global challenges of food and nutrition security by offering a sustainable source of protein and bioactive compounds. The capacity of legumes to establish symbiotic relationships with rhizobia bacteria enables biological nitrogen fixation (BNF), reducing the dependence on chemical fertilizers while enhancing soil health. However, the efficiency of this symbiosis is significantly influenced by environmental factors, such as soil acidity, salinity, temperature, moisture content, light intensity, and nutrient availability. These factors affect key processes, including rhizobia survival, nodule formation, and nitrogenase activity, ultimately determining the growth and productivity of legumes. This review summarizes current knowledge on legume-rhizobia interactions under varying abiotic conditions. It highlights the impact of salinity and acidity in limiting nodule development, soil temperature in regulating microbial community dynamics, and moisture availability in modulating metabolic and hormonal responses during drought and waterlogging. Moreover, the role of essential nutrients, including nitrogen, phosphorus, potassium, and trace elements such as iron, molybdenum, and boron, in optimizing symbiosis is critically analyzed.

The increase in the cost of fertilizers and their low efficiency has led, through nanotechnology, to the generation of new innovative products that are sustainable and improve the productivity of crops. Therefore, the objective of the present study was to evaluate the efficacy of a molybdenum nanofertilizer compared to two conventional fertilizers (chelate and sodium molybdate) applied via foliar combined with soil fertilization of NH4NO3 in relation to the Nitrogen Use Efficiency, growth and yield in green bean cv. Strike. Green bean plants cv. Strike were cultivated under controlled conditions in an experimental greenhouse and irrigated with nutrient solution. The treatments consisted of the foliar application of three Mo sources (Nano fertilizer, Mo Chelate and Sodium Molybdate) in four doses 0, 5, 10 and 20 ppm Mo, complemented with the edaphic application of four doses of NH4NO3 (0, 3, 6 and 12 mM of N). The results obtained indicate that the highest accumulation of biomass and yield were obtained with the application of NanoMo, with increases in biomass of 24.31% and 36.47% more in yield with respect to Chelate and Molybdate. Finally, it is concluded that the application of NanoMo improves the assimilation and efficiency of nitrogen use, reducing excessive applications of nitrogenous fertilizers without affecting the yield of the green bean crop. [ABSTRACT FROM AUTHOR]

Optimising fertilisation is an important part of maximising vegetable yield and quality whilst minimising environmental hazards. An accurate and efficient scheme of irrigation and fertiliser based on plants' nutrient requirements at different growth stages is essential for the effective intensive production of greenhouse pepper (Capsicum annuum L.). In this study, the effects of reducing fertilisation rate by 20%, 40%, 60% and 80% from the day 6 to day 0 before harvest for each layer of peppers on growth, yield, quality and nutrient utilisation were evaluated. The results showed that the morphological indicators (plant height and stem diameter) and biomass of plants decreased gradually with the increase in fertiliser reduction rate. Compared with control (CK) plants, the 20–40% reduction in fertiliser application rate did not cause a significant decrease in biomass and stem diameter but significantly increased the accumulation of N (13.52–15.73%), P (23.09% in 20% reducted-treatment) and K (13.22–14.21%) elements in plants. The 20–80% reduction in fertiliser application before harvest had no significant effects on the nutrient agronomic efficiency of N, P and K elements. However, it decreased the physiological nutrient efficiency and significantly improved the nutrient harvest index of N, P and K. Appropriate reduction in fertiliser application significantly increased the nutrient recovery efficiency (20–40% reduction) and nutrient partial-factor productivity (40% reduction) of N (3.35–6.00% and 12.87%), P (2.47–2.92% and 14.01%) and K (7.49–15.68% and 14.01%), respectively. Furthermore, reducing the fertilisation rate by 20–40% before each harvest had a certain positive effect on the C and N metabolism of pepper leaves and fruits. In particular, the activities of N metabolism-related enzymes (nitrate reductase, nitrite reductase, glutamine synthase, glutamate synthase and glutamate dehydrogenase) and C metabolism-related enzymes (sucrose phosphate synthase, sucrose synthetase, acid invertase and neutral invertase) in leaves and fruits did not significantly different or significantly increased compared with those in CK plants. The results of the representative aromatic substance contents in the fruit screened by the random forest model showed that compared with the CK plants, reducing the fertiliser application by 20–40% before harvest significantly increased the content of capsaicin and main flavour substances in the fruit on the basis of stable yield. In summary, in the process of pepper substrate cultivation, reducing the application of nutrients by 40% from the day 6 to day 0 before each harvest could result in stable yield and quality improvement of the pepper. These results have important implications for institutional precision fertilisation programs and the improvement of the agroecological environment. [ABSTRACT FROM AUTHOR]

Melatonin is a new plant hormone involved in multiple physiological functions in plants such as germination, photosynthesis, plant growth, flowering, fruiting, and senescence, among others. Its protective role in different stress situations, both biotic and abiotic, has been widely demonstrated. Melatonin regulates several routes in primary and secondary plant metabolism through the up/down-regulation of many enzyme/factor genes. Many of the steps of nitrogen metabolism in plants are also regulated by melatonin and are presented in this review. In addition, the ability of melatonin to enhance nitrogen uptake under nitrogen-excess or nitrogen-low conditions is analyzed. A model that summarizes the distribution of nitrogen compounds, and the osmoregulation and redox network responses mediated by melatonin, are presented. The possibilities of using melatonin in crops for more efficient uptake, the assimilation and metabolization of nitrogen from soil, and the implications for Nitrogen Use Efficiency strategies to improve crop yield are also discussed. [ABSTRACT FROM AUTHOR]

Simple Summary: China is not only a huge meat rabbit consumer but also the largest meat rabbit producer in the world, contributing a large amount of rabbit meat products to the domestic and foreign markets every year. Therefore, it is important for the domestic and international rabbit meat market to improve rabbit breeding production efficiency and rabbit meat quality based on the good use of domestic feed resources in China. It is well known that dietary amino acid nutrition is of great importance to animal growth. Lysine and methionine are limited in the common domestic rabbit feed sources in China, but they play an important role in rabbit growth. Moreover, different lysine and methionine compositions of the diets respond differently to rabbit growth. Consequently, the search for a better composition of dietary lysine and methionine is the main objective of this study. In recent years, ensuring food security has been an important challenge for the world. It is important to make good use of China's domestic local feed resources to provide safe, stable, efficient, and high-quality rabbit meat products for China and the world. Lysine and methionine are the two most limiting essential amino acids in the rabbit diet. However, little is known about the rational composition of lysine and methionine in rabbit diets and the mechanisms that affect growth and development. Accordingly, in this study, we sought to address this knowledge gap by examining the effects of different compositions of lysine and methionine in rabbit diets. Subsequently, the growth status, nitrogen metabolism, blood biochemical indexes, muscle development, muscle quality, and the growth of satellite cells were evaluated in the animals. The results showed that diets containing 0.80% Lys and 0.40% Met improved average daily weight gain, feed conversion, nitrogen use efficiency, and muscle quality in the rabbits (p < 0.05). Additionally, it altered the amino acid transport potential in muscle by upregulating the expression of the SLC7A10 gene (p < 0.05). Meanwhile, the cell viability and the rate of division and migration of SCs in the 0.80% Lys/0.40 % Met composition group were increased (p < 0.05). SLC38A2 and P–mTOR protein expression was upregulated in the 0.80% lysine/0.40% methionine composition group (p < 0.05). In conclusion, 0.80% Lys/0.40% Met was the most suitable lysine and methionine composition in all tested diets. SLC38A2 acted as an amino acid sensor upstream of mTOR and was involved in the 0.80% Lys/0.40% Met regulation of muscle growth and development, thus implicating the mTOR signaling pathway in these processes. [ABSTRACT FROM AUTHOR]