Plant glycerol-3-phosphate dehydrogenase (GPDH) catalyzes the reduction of dihydroxyacetone phosphate (DHAP) to produce glycerol-3-phosphate (G-3-P), and plays a key role in glycerolipid metabolism as well as stress responses. In this study, we report the cloning, enzymatic and physiological characterization of a cytosolic NAD+-dependent GPDH from maize. The prokaryotic expression of ZmGPDH1 in E.coli showed that the enzyme encoded by ZmGPDH1 was capable of catalyzing the reduction of DHAP in the presence of NADH. The functional complementation analysis revealed that ZmGPDH1 was able to restore the production of glycerol-3-phosphate and glycerol in AtGPDHc-deficient mutants. Furthermore, overexpression of ZmGPDH1 remarkably enhanced the tolerance of Arabidopsis to salinity/osmotic stress by enhancing the glycerol production, the antioxidant enzymes activities (SOD, CAT, APX) and by maintaining the cellular redox homeostasis (NADH/NAD+, ASA/DHA, GSH/GSSG). ZmGPDH1 OE Arabidopsis plants also exhibited reduced leaf water loss and stomatal aperture under salt and osmotic stresses. Quantitative real-time RT-PCR analyses revealed that overexpression of ZmGPDH1 promoted the transcripts accumulation of genes involved in cellular redox homeostasis and ROS-scavenging system. Together, these data suggested that ZmGPDH1 is involved in conferring salinity and osmotic tolerance in Arabidopsis through modulation of glycerol synthesis, stomatal closure, cellular redox and ROS homeostasis.

Plants are frequently confronted by diverse environmental stress, and the membrane lipids remodeling and signaling are essential for modulating the stress responses. Saline–alkaline stress is a major osmotic stress affecting the growth and development of crops. In this study, an integrated transcriptomic and lipidomic analysis was performed, and the metabolic changes of membrane lipid metabolism in maize (Zea mays) roots under saline–alkaline stress were investigated. The results revealed that phospholipids were major membrane lipids in maize roots, and phosphatidylcholine (PC) accounts for approximately 40% of the total lipids. Under 100 mmol NaHCO₃ treatment, the level of PC decreased significantly (11–16%) and the parallel transcriptomic analysis showed an increased expression of genes encoding phospholipase A and phospholipase D/non-specific phospholipase C, which suggested an activated PC turnover under saline–alkaline stress. The plastidic galactolipid synthesis was also activated, and an abnormal generation of C34:6 galactolipids in 18:3 plants maize implied a plausible contribution from the prokaryotic pathway, which could be partially supported by the up-regulated expression of three putative plastid-localized phosphatidic acid phosphatase/lipid phosphate phosphatase. A comprehensive gene–metabolite network was constructed, and the regulation of membrane lipid metabolism under saline–alkaline stress in maize was discussed.

This study investigated the influence of the exogenous application of vitamin B2 (VB2), B12 (VB12), biotin (VH), and nicotinic acid (VPP) on oxygen production in maize (Zea mays L.) seedlings at 5 °C for day 1, 3, 5 and 7. The seeds were soaked in VB2, VB12, VH, and VPP solutions for 24 h at the concentration of 100 mg/L, and control was soaked in distilled water. A total of 50 seeds were used for each treatment in germination boxes was repeated three times. The germination box was placed in a hypothermic incubator for 1, 3, 5, and 7 days in the dark at 5 °C, then moved to a plant growth room and kept for seven days. Compared with the VH and VPP treatments, the VB2 and VB12 treatments had higher thiobarbituric acid reactive substances, proline, and soluble sugars. The VB2 and VB12 treatments also increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) than other treatments. The VB2 and VB12 treatments reduced the contents of hydrogen peroxide (H2O2–), superoxide anion (O2–), and the damage of reactive oxygen species (ROS) to cells, increased the stability of the cell membrane and the content of cell osmoregulation substances. Moreover, VB2 and VB12 had higher seedling growth, germination rate, and index. Treatments VB2 and VB12 could promote maize seed germination and growth under low-temperature stress. Exogenous vitamins in crop production can be a valuable tool for protecting plants against low-temperature stress.

Biochar is a valuable soil amendment substance. However, no systematic study has investigated the effects of biochar on the microenvironment of saline-sodic soils and maize yield in cold areas of Heilongjiang Province. We investigated variations in soil physicochemical properties, soil bacterial and fungal community structure, maize root formation, plant dry matter accumulation, grain filling rate, and maize yield in saline soils treated with biochar (0, 20, 40, and 80 t/ha). Biochar improved saline soil properties and structure, slightly decreasing bulk density and pH and increasing the water-stable aggregate stabilization rate. Furthermore, the relative abundances of Sphingomonas, Lysobacter, Nitrospira, and Gemmatimonas and the fungal genus Guehomyces were increased, promoting the conversion of soil organic carbon and available nitrogen and phosphorus. Moreover, biochar reduced the relative abundance of some fungal pathogenic genera, including Fusarium, Gibberella, Cladosporium, Alternaria, and Epicoccum. However, shifts in soil bacterial and fungal community structure were indirectly driven by biochar-induced changes in soil physicochemical properties, with organic carbon as the most critical. Biochar promoted maize growth, development, and yield (root length, surface area, volume, dry matter accumulation, grain filling rate, and final weight). Biochar application at 40 t/ha had the greatest effect on soil microenvironment improvement, with the highest maize yield.

Phosphorus (P) in nature mostly exists in an insoluble state, and humic reducing microorganisms (HRMs) can dissolve insoluble substances through redox properties. This study aimed to investigate the correlations between insoluble P and dominant HRMs amenable to individual culture during biochar composting. These analyses revealed that, in comparison to the control, biochar addition increased the relative abundance of dominant HRMs by 20.3% and decreased redox potential (Eh) levels by 15.4% hence, enhancing the moderately-labile-P and non-labile-P dissolution. The pathways underlying the observed effects were additionally assessed through structural equation modeling, revealing that biochar addition promoted insoluble P dissolution through both the direct effects of bacterial community structure as well as the direct effects of HRMs community structure and indirect effects based on Eh of HRMs community structure. This research offers a better understanding of the effect of HRMs on insoluble P during the composting process.

Introduction: Humus can be formed during composting through biological pathways, nonetheless, the mechanisms through which bacterial and fungal communities govern the development of humus in compost with the addition of biochar remain uncertain.Methods: In this study, compost with cow dung and maize stover as feedstock was employed as a control group, and compost with 10% biochar added on top of the feedstock was adopted as a treatment group to investigate the effect of bacterial and fungal communities on humus formation during biochar composting.Results and Discussion: The results demonstrated that the humic acid content increased by 24.82 and 25.10% at the cooling and maturation stages, respectively, after adding biochar. Besides, the degree of polymerization content in the maturation stage was elevated by 90.98%, which accelerated the humification process of the compost. During the thermophilic and maturity stages, there was a respective increase of 51.34 and 31.40% in reducing sugar content, suggesting that the inclusion of biochar could furnish ample reducing sugar substrate for the Maillard reaction. The addition of biochar reduced the number of humus precursor-associated genera by 35, increased the number of genera involved in humus synthesis by two, and enhanced the stability of the cross-domain network between bacteria and fungi, which confirms that microorganisms contribute to the humification process by decreasing humus precursor consumption as well as increasing humus synthesis with the addition of biochar. Additionally, adding biochar could enhance the humification capacity of the compost pile by dominating the Maillard reaction with reducing sugars as the substrate and strengthening the function of humus synthesis-associated genera. This study enhances our comprehension of the regulatory pathways of biochar in the humification process during composting.