Aug 2026· Frontiers in Plant Science· Vol 17· 0 citations· 46 references
Medicine
Abstract
Onion bulb quality is largely defined by non-structural carbohydrates, phenolic antioxidants, and sulfur-containing flavor precursors, yet integrative evidence on how these domains respond to nitrogen imbalance under controlled conditions remains limited. A pot experiment applied four ammonium nitrate levels (N1–N4; 0.5–4.0 g NH4NO3 per pot) to two contrasting onion varieties (hybrid Hytech F1 and landrace Birnenförmige). Bulb morphology and quality traits were quantified alongside tissue elemental C:N ratios and a targeted trait–metabolite matrix covering carbohydrates, amino acids (including Allium-specific alk(en)yl cysteine sulfoxides, ACSOs), organic acids and other primary metabolites, as well as flavonoids, driven by higher dry matter and fructan-rich reserve pools in Birnenförmige versus higher soluble sugars and nitrogen-status metabolites in Hytech. Along the nitrogen gradient, bulb growth followed a non-linear response, peaking at intermediate supply and declining under oversupply, with a stronger high-N penalty in Hytech. Nitrogen oversupply increased nitrate and free amino acid pools and lowered elemental bulb C:N ratios, while total phenolic content and quercetin glycoside levels declined. In contrast, relative levels of putatively annotated ACSO-like compounds increased as pyruvate-based pungency decreased, consistent with a compositional decoupling between sulfur-containing compound profiles and the pyruvate-based pungency signal under high N. Together, the results identify variety-specific thresholds and coordinated trade-offs linking nitrogen status to growth and the major quality-related metabolic domains in onion bulbs.
Nitrogen (N) supply can influence the accumulation of sulfur (S)-containing metabolites that contribute to garlic (Allium sativum L.) flavour and quality, yet evidence of these responses under field conditions remains limited. Nine N application rates (0–360 kg ha−1) were evaluated under field conditions to examine the relationships between N supply, plant N and S status, and bulb S-containing metabolites. Allicin was quantified across three varieties, while alliin, γ-glutamyl-S-allyl-L-cysteine (GSAC), and alliin-to-allicin conversion were analysed in Glenlarge. The bulb alliin and allicin concentrations increased linearly with the N rate and were positively associated with the bulb N and S concentrations. The foliage N concentration was strongly positively correlated with the bulb alliin and allicin concentrations, suggesting that leaf N status may provide a useful predictor of S-containing metabolite accumulation. Sulfur K-edge X-ray absorption near-edge structure spectroscopy showed that the relative proportions of GSAC and alliin remained relatively consistent across the six N rates. This indicates that N supply was associated with the increased accumulation of S-containing compounds, without a substantial shift in their relative S speciation. The alliin and allicin concentrations increased up to the highest N rate tested (360 kg N ha−1), whereas increases in allicin yield became relatively small above approximately 200 kg N ha−1. Overall, these findings provide field-based evidence linking N nutrition with the accumulation of bioactive S-containing compounds in garlic and provide insights into how N supply may influence garlic quality under field conditions.
B. Nguyen, Bernhard J. Wehr, P. Kopittke et al.· Plants· 0 citations
Vanilla is a high-value crop whose demand exceeds supply, yet evidence-based nutrient management remains unexplored. This study investigated the effect of nitrogen form on vegetative growth, biomass allocation, and physiology of Vanilla planifolia in soilless culture. Ninety-five plants were assigned to five NO₃⁻-N: NH₄⁺-N ratios (0:100 to 100:0; n = 17 each) at 47 mg nitrogen L⁻¹ and a nitrogen-free solution (n = 10), over 140 days under controlled conditions. Total dry mass declined linearly with increasing ammonium proportion (p < 0.001), with relative growth rate the most responsive parameter: ammonium nutrition reduced total dry mass by 28% and relative growth rate by 36% relative to purely nitrate-fed plants. Increasing ammonium supply acidified the rhizosphere (substrate pH declined by 1.2 units, from 5.93 to 4.72) and tended to reduce leaf biomass fraction and total root length; tissue nitrogen concentration increased linearly with increasing ammonium proportion across all organs. A treatment × shoot-position interaction revealed temporally compounding growth advantages under nitrate nutrition. These results provide first evidence that nitrogen form, together with the accompanying shift in rhizosphere pH, shapes early vegetative growth in vanilla, with nitrate‑dominated supply producing the highest vegetative growth under the controlled soilless conditions tested.
Marvin Vahl, Finn Petersen, Jannis von Salzen et al.· Discover Plants· 0 citations
Nitrogen deprivation (N−) is widely used to induce lipid accumulation in microalgae. However, its impact on the relationship between lipid accumulation and thermochemical behavior remains poorly understood. In this study, a comparative experimental approach was used to evaluate the effects of nitrogen availability on growth kinetics, lipid accumulation, and pyrolysis-derived volatile compounds in Chlorella vulgaris, Scenedesmus obliquus, and Nannochloropsis oculata. Under nitrogen˗replete conditions (N +), all species showed higher growth rates, whereas N− reduced proliferation but increased lipid content by 5.0-fold in C. vulgaris, 2.4-fold in S. obliquus, and 1.8-fold in N. oculata. Py-GC/MS analysis revealed that N− shifted the pyrolysis profile toward lipid˗derived compounds, particularly C16˗C18 fatty acids, long˗chain alcohols, and hydrocarbons. In C. vulgaris, oleic acid (22.3%) and alcohol derivatives dominated; in contrast, N + conditions exhibited a more heterogeneous profile, including aromatics and sterols. N. oculata maintained a predominance of lipid-derived compounds, with N− associated with a higher contribution of oxygenated compounds. In S. obliquus, the pyrolysis profile under N + was characterized primarily by esters and reactive intermediates, while under N− it was dominated by hydrocarbons (13.6%) and alcohols. Nitrogen deprivation increased lipid accumulation in all three microalgal species, but the volatile compounds generated during pyrolysis remained species-dependent. Despite the higher lipid content under nitrogen deprivation, the corresponding pyrolysis profiles did not show a consistent relationship with lipid accumulation. These results indicate that lipid-rich biomass does not necessarily exhibit similar thermochemical behavior across microalgal species and suggest that evaluating feedstocks based solely on total lipid content may overlook species-specific differences relevant to bioenergy production.
Carlos Vicente Garza-León, H. C. Correa-Aguado, G. V. Cerrillo-Rojas et al.· Bioresources and Bioprocessi...· 0 citations
The mycelium of Phallus rubrovolvatus contains abundant metabolites with broad application prospects in functional foods and pharmaceuticals. However, how carbon and nitrogen substrate availability regulate the accumulation dynamics of mycelial metabolites remains under-explored. In this study, the supply levels of carbon (glucose) and nitrogen (peptone) were optimized to select high-biomass mycelia. Integrating nutritional activity assays with metabolomics and redundancy analysis, the regulatory mechanisms governing carbon–nitrogen metabolic flux were deciphered. The results demonstrated that mycelial nutritional content and antioxidant capacity exhibited a progressive upward trend under three distinct modes: carbon-driven, nitrogen-driven, and carbon–nitrogen synergistic-driven regimes. In the optimal carbon–nitrogen synergistic-driven group, the contents of total soluble sugars, reducing sugars, flavonoids, total phenolics, and soluble proteins increased by 72.06%, 160.80%, 52.47%, 113.69%, and 8.21%, respectively, compared with the control group. Meanwhile, the scavenging rates of superoxide anion, hydroxyl, ABTS, and DPPH free radicals increased by 14.12%, 24.09%, 14.77%, and 66.47%, respectively, compared with the control group. Differentially accumulated metabolites were significantly enriched in amino acid metabolism, energy metabolism, and secondary metabolite biosynthesis pathways. Carbon and nitrogen substrates reshaped intracellular metabolic flux, cooperatively regulating nutrient synthesis and intracellular redox equilibrium. This work reveals a cascade-linking relationship in which nutrient supply triggers metabolic remodeling, regulates oxidative balance, and drives pathway response. It provides theoretical support for the precision fermentation and industrial upgrade of P. rubrovolvatus, while offering a valuable reference paradigm for the high-value exploitation of other rare edible and medicinal fungi.
Xueli Li, Fu-Dong Huang, Tao Zhang et al.· Horticulturae· 0 citations
A four-tier closed-loop conceptual framework comprising signal perception, transport reprogramming, metabolic redistribution, and genetic redesign is developed that yields three testable predictions: the sequential activation of regulatory tiers; a quantitative relationship between Ca2+ signal amplitude and the extent of C–N metabolic redistribution; and salt-concentration thresholds that distinguish basal homeostatic buffering from full adaptive reprogramming.
Ran-Ran Liu, Long-Yu Wang, Shulei Wang et al.· Frontiers in Plant Science· 0 citations
Synthetic nitrogen fertilizers have greatly increased crop yields, yet much of the applied nitrogen is lost from agroecosystems and contributes to environmental pollution and higher economic costs. Improving nitrogen uptake efficiency (NUpE) benefits from understanding how root system architecture (RSA) governs soil nitrogen capture. Although root traits have seldom been explicit breeding targets, selection for variation in above-ground nitrogen accumulation has also likely shaped differences in RSA. The Illinois Protein Strain Recombinant Inbred population, derived from more than a century of divergent selection for seed protein concentration, offers a powerful resource for dissecting RSA variation. Using multi-year field phenotyping of excavated root crowns and genome-wide association analysis, we identified a quantitative trait locus on chromosome 10 containing E1OGDH1, which encodes the E1 subunit of the 2-oxoglutarate dehydrogenase (OGDH) complex. OGDH performs a key step in the tricarboxylic acid cycle that also modulates 2-oxoglutarate, an important entry point into nitrogen metabolism and a co-factor for enzymes involved in hormone and secondary product synthesis. Long-read sequencing of inbreds derived from the divergent IHP and ILP parental populations revealed promoter polymorphisms defining E1OGDH1 alleles and differed in E1OGDH1 expression in root tissue. Field experiments in IPSRI lines carrying IHP- or ILP-associated E1OGDH1 alleles showed differences in root architectural traits over two years. CRISPR-Cas9 knockout mutants confirmed a functional role for E1OGDH1 in whole-plant performance and nitrogen-responsive root development. Mutants were shorter, had reduced biomass, and exhibited altered architectural responses to soil nitrogen levels. Transcriptome analysis further showed that loss of E1OGDH1 altered basal and nitrogen-responsive expression of genes associated with root development and nitrogen uptake and metabolism. Together, these findings identify E1OGDH1 as a strong candidate quantitative regulator of maize RSA and nitrogen plasticity, suggesting that central carbon–nitrogen metabolic genes can contribute to root developmental responses relevant to NUpE.
Michelle S. Cho, Zhengbin Liu, Collin Luebbert et al.· bioRxiv· 0 citations
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