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Maize (Zea mays L.) is sensitive to salt stress, especially during seed germination and seedling morphogenesis, which limits maize growth and productivity formation. As a novel recognized plant hormone, melatonin (MT) participates in multiple growth and developmental processes and mediates biotic/abiotic stress responses, yet the effects of salt stress on maize seedlings remain unclear. Herein, we investigated the effects of 150 μM exogenous MT on multiple phenotypes and physiologic metabolisms in three-leaf seedlings across eight maize inbred lines under 180 mM NaCl salt stress, including growth parameters, stomatal morphology, photosynthetic metabolisms, antioxidant enzyme activities, and reactive oxygen species (ROS). Meanwhile, the six gene expression levels controlling antioxidant enzyme activities and photosynthetic pigment biosynthesis in two materials with contrasting salt resistance were examined for all treatments to explore the possible molecular mechanism of exogenous MT alleviating salt injury in maize. The results showed that 150 μM exogenous MT application protected membrane integrity and reduced ROS accumulation by activating the antioxidant system in leaves of maize seedlings under salt stress, their relative conductivity and H2O2 level average reduced by 20.91% and 17.22%, while the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) averaged increased by 13.90%, 17.02%, 22.00%, and 14.24% relative to salt stress alone. The improvement of stomatal size and the deposition of photosynthetic pigments were more favorable to enhancing photosynthesis in leaves when these seedlings treated with MT application under salt stress, their stomatal size, chlorophyll content, and net photosynthetic rate averaged increased by 11.60%, 19.64%, and 27.62%. Additionally, Gene expression analysis showed that MT stimulation significantly increased the expression of antioxidant enzyme genes (Zm00001d009990, Zm00001d047479, Zm00001d014848, and Zm00001d007234) and photosynthetic pigment biosynthesis genes (Zm00001d011819 and Zm00001d017766) under salt stress. At the same time, 150 μM MT significantly promoted seedling growth and biomass accumulation. In conclusion, our study may unravel crucial evidence of the role of MT in maize seedlings against salt stress, which can provide a novel strategy for improving maize salt stress resistance. [ABSTRACT FROM AUTHOR]

Low-temperature (LT) is one of the major abiotic stresses that restrict the growth and development of maize seedlings. Brassinolides (BRs) have been shown to enhance LT tolerance in several plant species; the physiological and molecular mechanisms by which BRs enhance maize tolerance are still unclear. Here, we characterized changes in the physiology and transcriptome of N192 and Ji853 seedlings at the three-leaf stage with or without 2 μM 2,4-epibrassinolide (EBR) application at 25 and 15 °C environments via high-performance liquid chromatography and RNA-Sequencing. Physiological analyses revealed that EBR increased the antioxidant enzyme activities, enhanced the cell membrane stability, decreased the malondialdehyde formation, and inhibited the reactive oxygen species (ROS) accumulation in maize seedlings under 15 °C stress; meanwhile, EBR also maintained hormone balance by increasing indole-3-acetic acid and gibberellin 3 contents and decreasing the abscisic acid level under stress. Transcriptome analysis revealed 332 differentially expressed genes (DEGs) enriched in ROS homeostasis, plant hormone signal transduction, and the mitogen-activated protein kinase (MAPK) cascade. These DEGs exhibited synergistic and antagonistic interactions, forming a complex LT tolerance network in maize. Additionally, weighted gene co-expression network analysis (WGCNA) revealed that 109 hub genes involved in LT stress regulation pathways were discovered from the four modules with the highest correlation with target traits. In conclusion, our findings provide new insights into the molecular mechanisms of exogenous BRs in enhancing LT tolerance of maize at the seedling stage, thus opening up possibilities for a breeding program of maize tolerance to LT stress. [ABSTRACT FROM AUTHOR]

Currently, the widely used active form of plant elicitor peptide 1 (PEP1) from Arabidopsis thaliana is composed of 23 amino acids, hereafter AtPEP1(1–23), serving as an immune elicitor. The relatively less conserved N-terminal region in AtPEP family indicates that the amino acids in this region may be unrelated to the function and activity of AtPEP peptides. Consequently, we conducted an investigation to determine the necessity of the nonconserved amino acids in AtPEP1(1–23) peptide for its functional properties. By assessing the primary root growth and the burst of reactive oxygen species (ROS), we discovered that the first eight N-terminal amino acids of AtPEP1(1–23) are not crucial for its functionality, whereas the conserved C-terminal aspartic acid plays a significant role in its functionality. In this study, we identified a truncated peptide, AtPEP1(9–23), which exhibits comparable activity to AtPEP1(1–23) in inhibiting primary root growth and inducing ROS burst. Additionally, the truncated peptide AtPEP1(13–23) shows similar ability to induce ROS burst as AtPEP1(1–23), but its inhibitory effect on primary roots is significantly reduced. These findings are significant as they provide a novel approach to explore and understand the functionality of the AtPEP1(1–23) peptide. Moreover, exogenous application of AtPEP1(13–23) may enhance plant resistance to pathogens without affecting their growth and development. Therefore, AtPEP1(13–23) holds promise for development as a potentially applicable biopesticides. [ABSTRACT FROM AUTHOR]

The efficient treatment of refractory organics in reverse osmosis concentrate (ROC) is a critical issue for achieving emission reduction or even zero emission in the petrochemical industry. A simple and efficient electrocatalytic process was proposed for treating actual petrochemical ROC using a highly active self-assembling Ti/SnO 2 -Sb anode. The Ti/SnO 2 -Sb anode was prepared by using citric acid (CA) and ethylene glycol (EG) as precursors, with a mole ratio of Sn:Sb of 5:1 and a metal salts to CA to EG mole ratio of 1:3:16. The resulting electrode surface had a complete mesh pit structure after calcination at 550 ºC. Several key factors were found to affect the degradation of dissolved organic carbon (DOC), including current density, chloride ion concentration, Fe (II) concentration, and acidity. The presence of chloride ions on the anode surface significantly improved the conversion efficiency of hydroxyl radicals, which played a crucial role in the oxidation of the organics. Additionally, near the cathode, oxidative radicals such as H 2 O 2 and O 2 -∙ were generated, while hydroxyl radicals were produced with the addition of Fe (II) and H+. Under a current density of 20 mA·cm−2, the Ti/SnO 2 -Sb anode achieved a COD removal rate of 94.5% and a DOC removal rate of 43.4%. [Display omitted] [ABSTRACT FROM AUTHOR]