TL;DR
A mechanistic framework for understanding how pulse crops reprogram their primary metabolism to survive high-phenolic organic waste exposure is provided, highlighting the dual nature of OMW as both a phytotoxin and a potential metabolic stimulus.
Cadmium (Cd) is considered one of the most mobile and toxic environmental contaminant on all organisms. This study aimed to remove the toxicity effect of Cd with important natural materials without harmful side effect on the living organisms. Two concentrations (1% and 2%) of biochar and nano-biochar (with an average particle size of 15.13 nm) were applied to Vicia faba L. under Cd stress (200 µM) by adding them to Hoagland’s nutrition solution. Results indicated that Cd significantly decreased plant growth parameters (root and shoot length, fresh and dry weights of shoot and root and leaf area) and chlorophyll levels under Cd stress. Cd elevated the antioxidant enzymes and proline levels. The genes that are engaged in the melatonin pathway (N-acetylserotonin, methyltransferase, Serotonin N-acetyltransferase slightly interacted (if any) with Cd stress. Caffeic acid O-methyltransferase (COMT) only showed a significant response to Cd, with a 3.74-fold increase in expression at the first time-point. At the same time, biochar and nano-biochar effectively reduced the harmful effects of Cd on plant growth, improved physiological responses, and modulated the expression of the COMT gene. Nano-biochar exhibited particularly strong improvements across various growth parameters. This is the first time studying these genes in Vicia faba plants under any stress. COMT is involved in other pathways such as lignin pathway and might be expressed in response to Cd stress as a part of this pathway.
Mulberry (Morus alba L.) leaves are widely used as functional food and medicinal-food raw materials, yet the influence of soil microplastic contamination on their quality formation remains insufficiently understood. In this study, a 45-day pot experiment with 3–4 biological replicates was conducted to compare the effects of conventional polyethylene (PE) and biodegradable poly (butylene succinate) (PBS) microplastics at graded soil application rates on mulberry seedling growth, tissue ultrastructure, antioxidant-related quality attributes, and metabolic profiles. PE and PBS suppressed mulberry height, stem diameter and biomass in a dose-dependent way (p < 0.05). At 400 mg/kg, PE reduced plant height, stem diameter and fresh biomass by 34.7%, 30.8% and 31.4%, while PBS caused larger declines of 45.5%, 39.8% and 42.5%; total dry biomass dropped maximally by 34.2% under PE and 46.8% under PBS. Both treatments triggered 31.8% compensatory root elongation potentially for nutrient capture, yet PBS induced more severe root pore blockage and leaf cuticle damage than PE across tested concentrations. MP exposure raised leaf total flavonoids and phenolics markedly. At 400 mg/kg, PE and PBS boosted flavonoids by 82.8% and 90.9%, phenolics by 90.1% and 100.8%. Meanwhile, 400 mg/kg PE and PBS increased DPPH activity by 65.9% and 73.5%, ABTS activity by 66.3% and 74.4% relative to the control. Non-targeted metabolomics demonstrated pronounced shifts in the leaf metabolic profiles, characterized by the accumulation of coumaric acid, quercetin, and rutin, while glutathione levels declined. KEGG analysis identified phenylpropanoid and flavonoid biosynthesis as core responsive pathways; high PBS levels strongly disturbed lipid and stress metabolism. Overall, microplastic stress induced a trade-off between vegetative growth and antioxidant-oriented secondary metabolism in mulberry leaves. These findings suggest that biodegradable PBS residues can induce prominent physiological variations during the initial crop production stage, which highlights the need to closely track their temporal effects on functional raw materials.
Maize (Zea mays L.) is a major staple crop worldwide and plays a critical role in food security. Although humic acid (HA) is widely used to improve crop productivity, its effectiveness is often limited by poor dispersibility and bioavailability. Herein, nanohumic acid (NHA) with improved dispersibility was synthesized, and its effects on maize yield and underlying mechanisms were evaluated. The results showed that NHA significantly promoted maize growth and increased yield, with the highest yield under NHA15 (15 mg/kg; 31.8 g/plant), exceeding HA15 (12.8 g/plant) and CK (6.8 g/plant). Maize yield responded to NHA were concentration-dependent, showing stimulation at low doses but inhibition at high doses. NHA also enriched bacterial taxa associated with plant growth and nutrient availability and upregulated grain tryptophan metabolism, increasing IAA contents by 35.1% and 108.3% relative to CK and HA, respectively. These findings support the application of NHA for maize yield improvement.
This study evaluated the effectiveness of consortium-based microbial preparations (EM (Effective Microorganisms), EM-1, EM Agro and EM Bioactive) in degrading phenolic compounds and regenerating nutrient solution in portable ebb-and-flow hydroponic systems during sweet pepper (Capsicum annuum L.) cultivation under controlled conditions, using vertical portable hydroponic units. Microbial preparations were applied to the nutrient solution every 14 days. Total phenolic content, biometric parameters, chlorophyll content (SPAD index, Soil and Plant Analysis Development), nutrient solution parameters and phytotoxicity were assessed. Without regeneration, phenolic compounds accumulated to 458.6 ± 31.4 mg L⁻¹ over 90 days, reducing plant productivity by 51.1 %. A strong significant negative correlation using Spearman’s rank correlation coefficient with perfect rank-order reversal, rs = -1.0, p = 0.017 was found between phenolic compound concentration and productivity. All microbial preparations effectively degraded phytotoxic exudates, with EM Bioactive showing the highest efficiency (89.4 %). This treatment increased plant productivity compared with complete nutrient solution replacement, while reducing water and fertilizer consumption and lowering solution phytotoxicity to a low-toxicity level. The findings indicate that microbial degradation of root exudates is an effective strategy for nutrient solution regeneration, improving environmental sustainability, and resource efficiency of closed portable hydroponic systems for sweet pepper cultivation. As the study was limited to a single crop and a single 90-day cultivation cycle, these conclusions regarding the ecological sustainability of urban farming and closed hydroponic systems more broadly should be regarded as preliminary, pending validation on other vegetable crops (e.g., tomato, cucumber, lettuce) and over multiple nutrient-solution reuse cycles.
Olive tree (Olea europaea L.) cultivation is increasingly challenged by climate change and the necessity for more sustainable crop management strategies. In this context, plant biostimulants have emerged as inputs of high potential for improving crop performance and resilience. Nonetheless, knowledge of their underlying biochemical mechanisms remains largely fragmented. Here, an untargeted GC/EI/MS-based metabolomics approach was employed to investigate the early metabolic responses of young olive trees to foliar application of two commercial biostimulants: a seaweed (SE)- and a harpin (HRP)-based formulation. Leaf samples were collected seven days post-treatment and were subjected to photosynthetic-content and metabolomics analyses. The former revealed no statistically significant differences in chlorophyll and carotenoid contents among treatments, indicating that photosynthetic pigment homeostasis was maintained. In contrast, metabolomics analysis demonstrated extensive and coordinated metabolic reprogramming induced by both products. SE treatments resulted in a primarily promoted growth-oriented metabolic profile, characterized by enhanced carbon utilization, modulation of antioxidant metabolism, activation of plastidial isoprenoid biosynthesis, and remodeling of the shikimate–phenylpropanoid pathway. Conversely, HRP treatments elicited a distinct stress-priming signature involving the accumulation of α,α-trehalose, phytol, and α-ketoglutaric acid, together with membrane lipid remodeling associated with improved osmoprotection and stress acclimation. These findings provide novel insights into the mode(s) of action of olive biostimulants and highlight the importance of metabolomics for identifying biochemical markers associated with enhanced plant resilience and sustainable olive production.
