Qiang Zhao

In salinized soils, high salt and pH inhibit iron availability via chelation and ion competition, inducing iron deficiency stress in plants. Compared with traditional iron fertilizers, nano‐iron has characteristics like easy absorption and targeted slow release, showing great potential in improving plants' saline‐alkali tolerance. Herein, a spherical‐like nano‐iron (average particle size of 20–50 nm, zeta potential of −25 mV, and with oxide layer) was synthesized. Soybean cultivars Hefeng 50 (HF50) and Henong 95 (HN95) were grown in pots filled with soil treated with mixed saline‐alkali solution (NaCl: Na ₂ SO ₄ : Na ₂ CO ₃ : NaHCO ₃ = 1: 9: 1: 9, pH = 8.9) to investigate the effects of foliar application of 0–300 mg l ⁻¹ nano‐iron on soybean growth. Foliar nano‐iron significantly alleviated saline‐alkali stress induced growth inhibition, with 200 mg l ⁻¹ as the optimal concentration. Nano‐iron enhanced antioxidant enzymes activities in soybean leaves and roots under saline‐alkali stress, reduced cellular H ₂ O ₂ and O ₂ ⁻ contents, mitigated membrane lipid peroxidation, and improved osmotic adjustment capacity. It up‐regulated the expression levels of genes related to chlorophyll biosynthesis, light absorption, electron transport, and carbohydrate metabolism, increased chlorophyll content, promoted the efficiency of light absorption and utilization in soybean leaves, accelerated carbohydrate biosynthesis, and provided a material and substrate basis for plant stress‐resistant physiological regulation. Ultimately, the 200 mg l ⁻¹ nano‐iron treatment significantly increased the number of seeds per plant, seed weight per plant, and 100‐seed weight of both soybean cultivars. This study provides the basis for developing nano‐iron‐based soybeans saline‐alkali tolerant cultivation technologies.

Soil salinization and alkalization severely threaten global agricultural sustainability. Although N-acetylcysteine (NAC) is well known as an antioxidant in animal research, its effects on plant salt–alkali tolerance and the underlying mechanisms remain unclear. This study investigated the regulatory effects of foliar-sprayed NAC on two soybean (Glycine max) cultivars—salt-tolerant HF50 and salt-sensitive HN95—under saline–alkali stress. Exogenous NAC alleviated seedling growth inhibition by supplying cysteine, which elevated glutamate–cysteine ligase (GCL) activity and promoted homoglutathione (hGSH) accumulation. It further strengthened the ascorbic acid (AsA)–glutathione/homoglutathione ((h)GSH) cycle and elevated antioxidant enzyme activities, thereby relieving oxidative injury, while also activating DNA repair pathways to preserve genomic stability and protecting chloroplast and mitochondrial integrity. Notably, distinct genotype- and tissue-specific responses to NAC were detected. HN95 relied primarily on root antioxidant defenses in a strongly concentration-dependent manner, whereas HF50 coordinated antioxidant metabolism and DNA repair more effectively, showing consistent responses to NAC concentrations. These findings elucidate the coordinated physiological and molecular mechanisms by which exogenous NAC mitigates saline–alkali damage in soybean, providing a theoretical foundation for using NAC to enhance crop stress resilience and develop sustainable cultivation techniques for saline–alkali soils.

Saline–alkali stress is a widespread abiotic stress that severely impairs crop growth and yield formation. Iron Chlorin e6 (ICe6), a novel plant growth regulator, is essentially a chlorophyll derivative, and possesses potential application value in regulating plant chlorophyll metabolism and improving plant stress resistance. In this study, the saline–alkali-sensitive soybean cultivar Henong 95 and saline–alkali-tolerant soybean cultivar Hefeng 50 were used as experimental materials, and foliar spraying with 120 nmol/L ICe6 was conducted at the R1 stage. The results indicated that relative to CK, SA treatment markedly inhibited soybean growth, accompanied by reduced antioxidant capacity, excessive reactive oxygen species (ROS) accumulation and significantly lowered photosynthetic pigment content. Carbohydrate accumulation was substantially suppressed, which ultimately resulted in yield reduction (HN95: −12.31%; HF50: −11.08%). ICe6 treatment mitigated saline–alkali-induced growth inhibition in soybean plants, as reflected by markedly restored antioxidant indices, sharply decreased malondialdehyde (MDA), H₂O₂, and O₂⁻ levels, and notably increased leaf area (HN95: +49.72%; HF50: +19.82%) and chlorophyll content (HN95: +36.06%; HF50: +90.75%). Combined transcriptomic and metabolomic profiling showed that, relative to the SA control, ICe6 treatment led to the identification of 2896 DEGs in HN95 and 3530 DEGs in HF50, with significant enrichment in photosynthesis- and chlorophyll metabolism-related pathways, e.g., GO:0009765 (photosynthesis, light harvesting). Differential metabolites were chiefly enriched in isoflavonoid biosynthesis—a source of antioxidants—and amino acid biosynthesis, which governs chlorophyll precursor synthesis. These findings suggest that ICe6 may enhance chlorophyll content by modulating the expression of genes involved in chlorophyll metabolism, contributing to light capture and chlorophyll biosynthesis, facilitating carbohydrate accumulation and ultimately contributing to increased yield under saline–alkali stress (HN95: +5.74%; HF50: +5.83%).

The GmSNAT1 gene, which encodes a key enzyme involved in soybean melatonin biosynthesis, is crucial for abiotic stress tolerance. In the present study, the molecular mechanism by which GmSNAT1 enhances cold tolerance is elucidated. The cold tolerance of plants was significantly increased by GmSNAT1 overexpression and reduced by CRISPR/Cas9-mediated knockout, a phenotype that was effectively rescued by exogenous melatonin. Integrated transcriptomic, physiological, and biochemical analyses revealed that the GmSNAT1-mediated melatonin pathway activates calcium signaling; coordinates the crosstalk between auxin, abscisic acid, and ethylene; and mobilizes transcription factor networks to orchestrate bidirectional physiological responses. Additionally, the activation of antioxidant systems for reactive oxygen species scavenging and the upregulation of photosynthesis-related genes to maintain photosynthetic stability were explored. The physical interaction between GmSNAT1 and the plant sulfotyrosine peptide receptor GmPSYR1 was confirmed using co-immunoprecipitation, bimolecular fluorescence complementation, and yeast 2-hybrid assays. This interaction may be involved in cold stress signal transduction, regulation of root development, and redox homeostasis through GmPSYR1. Collectively, these findings demonstrate that cold adaptation in soybeans is synergistically enhanced by GmSNAT1 via a multidimensional axis encompassing melatonin synthesis, signal transduction, and physiological protection, thereby providing a novel molecular target for breeding cold-tolerant crops.

Saline‐alkali stress, a widespread abiotic stress worldwide, severely affects the growth, development, and yield formation of crops. Nanomaterials show great potential in regulating plant growth and improving stress resistance due to their unique physical and chemical characteristics. In this study, nano‐silicon dioxide (nano‐SiO ₂ ) was prepared by the sol–gel method and used to construct a highly efficient melatonin delivery system. Soybean cultivars Hefeng 50 and Henong 95 were field‐grown in saline‐alkali soil and foliar‐sprayed with 200 mg/L nano‐SiO ₂ , 300 μM melatonin (MT), or their combination at the V3 stage. In the melatonin–nano‐SiO ₂ system, the encapsulation efficiency and drug‐loading capacity of melatonin by nano‐SiO ₂ were 35% and 53%, respectively. The system can significantly enhance melatonin photostability. The melatonin–nano‐SiO ₂ treatment significantly enhanced the antioxidant enzyme activity and regulated glutathione levels in soybean plants and reduced the accumulation of reactive oxygen species. The results of physiology, RNA‐seq, and qRT‐PCR indicated that melatonin–nano‐SiO ₂ treatment can repair photosynthetic carbon metabolism damage induced by saline‐alkali stress. Specifically, it increased leaf area, photosynthetic pigment content, photosystem II (PSII) efficiency, and gas exchange parameters of leaves. It also promoted the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SuSy), while inhibiting the activities of α ‐amylase and β ‐amylase, thereby enhancing soluble sugar, sucrose, and starch accumulation. Ultimately, melatonin–nano‐SiO ₂ treatment significantly improved pod number per plant, seed number per plant, and 100‐seed weight. Compared to saline‐alkali stress, the per plant yield of HF50 and HN95 under melatonin–nano‐SiO ₂ treatment increased by 77.41% and 76.52%, respectively.

The DNA mismatch repair (MMR) system plays a crucial role in repairing DNA damage and regulating cell cycle arrest induced by cadmium (Cd) stress. To elucidate the mechanism by which miRNAs target AtMSH2 in regulating Arabidopsis’ response to Cd stress, the wild-type Arabidopsis, Atmsh2 mutant, and three miRNA-overexpressing transgenic lines were grown hydroponically in half-strength MS solution containing cadmium (Cd) at concentrations of 0, 0.5, 1, 2, and 3 mg/L for 5 days. miRNA-seq analysis, bioinformatics prediction, dual-luciferase reporter assays, and qRT-PCR results demonstrated that miR5651, miR170-3p, and miR171a-3p specifically targeted AtMSH2 and their expression levels showed a significant negative correlation. Compared to wild-type (WT) Arabidopsis, Cd stress tolerance was significantly enhanced in miRNA-overexpressing transgenic lines. Moreover, exogenous application of these three miRNAs in half-strength MS liquid medium also markedly improved Cd stress tolerance in wild-type Arabidopsis. Furthermore, the expression of these three miRNAs expression was further upregulated by Cd stress in a dose-dependent manner. Additionally, DNA damage response in miRNA-overexpressing transgenic lines was promoted based on the expression of DNA repair, DNA damage signaling, and cell cycle genes, which differed from both wild-type and Atmsh2 plants. Taken together, miR5651, miR170-3p, and miR171a-3p participated in Cd stress response and improved plant Cd tolerance by mediating the expression of AtMSH2. Our study provides novel insights into the epigenetic mechanisms of Cd tolerance in plants, which sheds light on breeding for stress resilience in phytoremediation.

Saline‐alkali (SA) stress is one of the most widespread abiotic stresses affecting plant growth and productivity worldwide. Melatonin is an auxin‐like analogue that can improve plant tolerance to multiple abiotic stresses. Herein, two soybean cultivars, Heihe 49 and Henong 95 were pot cultured and treated with 80 mM SA stress solution (mixed with NaCl:Na ₂ CO ₃ :NaHCO ₃ :Na ₂ SO ₄ = 1:1:9:9) at the V1 stage. The 0–300 μM melatonin was foliar sprayed at the V3 stage to explore the effects of exogenous melatonin treatments on soybean plant growth at the grain‐filling stage under SA stress. Compared with the control, SA stress significantly reduced the growth, biomass accumulation and yield of both soybean cultivars. As expected, melatonin treatments significantly increased the plant height, stem diameter, shoot dry weight and pod number of soybean plants under SA stress. In addition, MT treatments significantly increased the chlorophyll content, gas exchange and chlorophyll fluorescence parameters of soybean leaves under SA stress, which were conducive to the accumulation of soluble sugars, sucrose, fructose and starch in the leaves, pod skins and grains. MT treatments promote the carbohydrate metabolic cycle by increasing the activity of sucrose and starch‐metabolizing enzymes and upregulating the expression levels of correlative genes in the leaves, pod skins, and grains of both soybean cultivars. MT treatments upregulated the expression levels of GmSWEETs and GmSUC2 in soybean tissues to increase the transportation of sucrose into grains, promote grain development, and finally increase soybean yield under SA stress.

Cadmium (Cd) is a highly hazardous heavy metal that has an extensive impact throughout the world. 2,4-Epibrassinolide (BR) is an endogenous hormone that can enhance plant tolerance to various abiotic stresses. Herein, Vigna angularis cultivar “Zhen Zhuhong” was grown hydroponically and treated with 0, 1, and 2 mg·L⁻¹ cadmium chloride (CdCl₂) at the V1 stage, and foliar sprayed with or without 1 μM BR solution to analyze the effects of BR treatment on the physiology of Vigna angularis seedling leaves under Cd stress. BR treatment significantly alleviated the growth inhibition induced by Cd stress, which was associated with an increase in the plant height (11.15–17.83%), leaf area (35.59–56.72%), leaf dry weight (45.57–50.65%), and above-ground dry weight (50.86–55.17%). In addition, BR treatment induced significant reductions in Cd accumulation across different tissues of V. angularis, with decreases of 20.38–35.93% in leaves, 21.24–32.74% in stems, and 15.38–16.00% in petioles. Compared with the Cd treatment, BR treatment significantly enhanced the activities of peroxidase (5.02–13.22%), ascorbate peroxidase (27.13–70.28%), catalase (20.46–32.30%), and superoxide dismutase (16.54–21.81%), and increased the ascorbic acid content (27.55–45.52%), which contributed to a reduction in the accumulation of reactive oxygen species, cellular membrane damage, and cytoplasmic exosmosis. RNA-seq and real-time quantitative reverse transcription PCR analyses revealed that the BR treatment under Cd stress significantly upregulated the expression of genes involved in chlorophyll biosynthesis, transformation, and degradation, thereby enhancing the chlorophyll cycle. Furthermore, the BR treatment significantly increased the number of grana lamellae in the mesophyll cells, which enhanced the biosynthesis of chloroplasts. The increase in the chlorophyll content improved the capture of light energy, electron transport in photosynthesis, and the biosynthesis and metabolism of carbohydrates in the leaves of V. angularis under Cd stress.