Sedum alfredii is a cadmium (Cd) hyperaccumulator, but the regulatory mechanisms linking phytohormones and redox balance to Cd transporter expression remain unclear. In this study, we omitted external cadmium (Cd) stress to isolate and examine the interplay between phytohormone and reactive oxygen species (ROS) signaling. Exogenous treatments with abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA₃), trans-zeatin (t-Z), and H₂O₂ were combined with analyses of hormone levels, antioxidant enzyme activities, and transporter gene expression. Correlation and PLS-SEM analyses identified the CAT–H₂O₂ module as a key node: ABA and IAA enhanced CAT activity and alleviated ROS-mediated repression of transporters, while GA₃ and t-Z exerted opposite effects. Functional validation using an H₂O₂ scavenger revealed that the regulation of HMA3 and Nramp5 by ABA and t-Z is H₂O₂-dependent. In contrast, IAA modulates Nramp5 through a ROS-independent pathway, while the regulatory effects of GA₃ were negligible. Functional validation under Cd exposure suggests a model wherein HMA3 and Nramp5 act in a complementary manner to sequester and redistribute Cd in leaves, thereby supporting hyperaccumulation. These findings highlight hormone-specific ROS pathways as central to transporter regulation and provide mechanistic insights to improve phytoremediation efficiency.

To determine whether photoperiod influences integrated physiological and molecular mechanisms underlying cadmium (Cd) uptake and tolerance in Sedum alfredii, plants were exposed to varying day lengths (2-24 h). Distinct photoperiod-dependent trends emerged: very short photoperiods primarily stimulated stress-related hormone signaling and early-stage flavonoid synthesis, while an intermediate photoperiod (~10 h) concurrently enhanced growth-promoting hormones, jasmonate signaling, and antioxidant defenses. This optimal photoperiod elicited a coordinated peak in phytohormonal responses, antioxidant enzyme activities, and Cd transporter gene expression. Canonical correspondence analysis identified three major co-regulatory modules integrating hormonal signaling, secondary metabolism, and heavy-metal transport. These modules included an auxin - IAA oxidase network, an ABA - phenolic metabolism axis linked to key metal transporter genes (HMA and ZIP families), and a cytokinin - flavonoid pathway associated with additional Cd transporters. The convergence of these modules underscores a systemic regulatory mechanism balancing plant growth, defense responses, and heavy-metal management. These findings provide a mechanistic understanding of how photoperiodic signals modulate endogenous hormone networks and associated molecular processes to optimize Cd accumulation and tolerance. This study thus identifies photoperiod as a pivotal environmental cue that could inform strategies to enhance S. alfredii's effectiveness in phytoremediation of Cd-contaminated soils.

Agricultural pesticides are significant drivers of antibiotic resistance in soil. However, the differential impacts of antibiotic versus non-antibiotic pesticides on the soil resistome are poorly characterized. Here, we analyzed sequencing data from soils exposed to either antibiotic or non-antibiotic pesticides to compare differences in antibiotic resistance gene (ARG) burden, diversity, assembly processes, network topology, and host taxonomy. Soils exposed to antibiotic pesticides exhibited a significantly higher ARG burden (0.52% vs. 0.27% of total genes), whereas soils exposed to non-antibiotic pesticides showed significantly higher alpha diversity (p < 0.05). ARG community compositions also differed significantly between antibiotic and non-antibiotic exposures (PERMANOVA, R² = 0.215, p < 0.001). Assembly analysis using the modified stochasticity ratio indicated that deterministic processes governed ARG community assembly in both groups, with stronger influence observed in non-antibiotic soils. Co-occurrence network analysis revealed contrasting patterns. A compact, highly centralized network emerged in antibiotic-exposed soils, while a larger, more dispersed network characterized non-antibiotic soils. In both networks, aminoglycoside ARGs served as keystone nodes, accompanied by the β-lactam ARG in antibiotic soils and the macrolide ARG in non-antibiotic soils. Pseudomonadota was the predominant ARG host (>60% contribution) across both exposures, though many other phyla exhibited significance (p < 0.05) between group differences in their ARG contributions. Non-pathogenic bacteria comprised the majority of ARG hosts in all samples. When examining ARG contributions from pathogenic hosts, zoonotic and animal-associated pathogens contributed significantly (p < 0.01) more in non-antibiotic soils than in antibiotic soils, whereas the ARG contribution from plant pathogens was comparable between the two pesticide groups. Overall, our study suggests that antibiotic and non-antibiotic pesticides shape distinct ARG network patterns and host–pathogen profiles, posing distinct risks to public health and agricultural ecosystems.

Sugarcane productivity varies widely among genotypes, but the biochemical traits underlying these differences remain poorly characterized. In this study, six contrasting sugarcane cultivars were profiled to investigate how ionomic, hormonal, flavonoid, and photosynthetic pigment signatures are associated with yield and sucrose accumulation. Morphological traits and field performance revealed marked genotypic variation, with ZZ14 and GL1215 achieving the highest yields and sugar content, while GT59 and GT60 performed less favorably. Multivariate analyses of ionomic data showed that potassium, magnesium, and calcium were consistently enriched in high-yield cultivars, whereas sodium, boron, and manganese were negatively associated with growth traits. Hormone profiling revealed that high-yielding genotypes utilize diverse strategies: while the high-yielding GL1215 achieved superior sugar content with the lowest levels of growth-promoting hormones, the LT1790 genotype, despite having the highest levels of these hormones, showed suboptimal yield due to a costly trade-off with its hyperactive defense system. Flavonoid analysis indicated that LT1790 contained the highest levels of Quercetin, rutin, and caffeic acid, suggesting enhanced antioxidant capacity, whereas GT59 preferentially accumulated chlorogenic acid. Canonical correlation analysis confirmed that nutrient balance and metabolite composition strongly correlated with plant height, stem diameter, and sugar concentration. Together, these results suggest that high-yield sugarcane genotypes achieve a superior metabolic balance, combining efficient nutrient uptake and robust antioxidant capacity with a favorable hormone profile that promotes strong growth without triggering a costly constitutive defense system.

This study investigates the impact of different arsenic (As) species (arsenite (As³⁺), arsenate (As⁵⁺), and their mixture) on Litchi chinensis Sonn. fruit quality and underlying mechanisms through foliar spray treatments on 3-year-old litchi trees. The results revealed that As accumulation and distribution vary significantly across tissues, with leaves and peels exhibiting 40 times higher As levels than those in the flesh. As³⁺ treatment resulted in the highest total As accumulation in fruits by the end of ripening, whereas mixed treatments prolonged the persistence of bioavailable As (particularly As³⁺), leading to sustained stress. As exposure reduced yields by an average of 36 % (As³⁺) and moderately inhibited fruit development (As⁵⁺ and mixed treatment). Mechanistically, As speciation reshaped the sugar-acid metabolic network primarily by modulating the PPC-MDH axis. The analysis revealed that As exposure upregulated PPC and MDH pathways, redirecting carbon flux toward ascorbate-derived organic acid accumulation (e.g., tartaric acid), while increased TCA cycle activity negatively regulated sugar accumulation. Mixed treatments induced complex shifts in gene expression, reflecting the combined effects of oxidative stress and metabolic perturbations. Notably, As³⁺ exhibited 10-fold higher toxicity than As⁵⁺ due to stronger thiol group binding and enzymatic inhibition. These findings underscore the risks of As contamination in litchi production, underscoring the need for monitoring As species in fertilizers and mitigating their accumulation to ensure food safety and sustainability.

Zinc (Zn) can modify plant growth and stress acclimation under cadmium (Cd) exposure; however, whether Zn consistently mitigates Cd accumulation across rice cultivars remains unclear. Here, 44 rice cultivars were exposed to Cd alone or Cd + Zn under controlled hydroponic conditions to evaluate the effects of Zn on Cd uptake and root-to-shoot translocation. Zn co-exposure resulted in highly divergent Cd responses among the cultivars. The response landscape revealed four interaction types, with response intensities spanning a nearly 200-fold range. Notably, shoot Cd levels increased in 19 of the 44 cultivars, indicating that Zn did not uniformly reduce aboveground Cd accumulation. Random Forest analysis distinguished the response direction with approximately 70% accuracy, whereas the response magnitude was less predictable. Further analysis of 12 representative cultivars identified layer-specific candidate structures, revealing that translocation-related variation was mainly associated with root superoxide/flavonoid traits, shoot Cd accumulation with flavonoid/hormone traits, and total Cd response amplitude with phenolic/flavonoid traits. Together, these results show that Zn-mediated Cd responses in rice are strongly cultivar-dependent and may be linked to distinct physiological response states, particularly root redox-related traits. These findings identify cultivar-specific physiological response states associated with the direction of Zn-mediated Cd redistribution, rather than supporting the universal protective effect of Zn.