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Abstract: Medicago varia is a very important legume forage with a high yield and good nutrient quality. It is widely cultivated in the middle‐eastern regions of China. However, drought is one of the major abiotic stresses that reduce Medicago varia growth and production. 5‐aminolevulinic acid (5‐ALA) is a physiologically active substance in plants with the potential to improve agricultural production. Exogenous application of 5‐ALA is able to increase plant resistance to multiple abiotic stresses. In this study, the effects of different concentrations of 5‐ALA (0, 5, 10, 20, 30 mg L−1) on seed germination and seedling growth of Medicago varia under drought stress was investigated. The results showed that seed germination was reduced significantly under drought stress. However, exogenous 5‐ALA significantly increased the final germination percentage (FGP) and reduced mean germination time (MGT), indicating that 5‐ALA promoted seed germination of Medicago varia under drought stress. In addition, the rate of cotyledon protruding seed coat, seedlings biomass, radicle length, chlorophyll content of cotyledon, aperture width of stomata and pore area of stomata were increased significantly and stomatal density of cotyledon was reduced significantly by 5‐ALA under drought stress. Collectively, our data suggest that 5‐ALA can be applied to promote seed germination of M. varia under drought stress. [ABSTRACT FROM AUTHOR]

ABSTRACT myo-Inositol phosphate synthase (MIPS) is the key enzyme of myo-inositol synthesis, which is a central molecule required for cell metabolism and plant growth as a precursor to a large variety of compounds. A full-length fragment of MfMIPS1 cDNA was cloned from Medicago falcata that is more cold-tolerant than Medicago sativa. While MfMIPS1 transcript was induced in response to cold, dehydration and salt stress, MIPS transcript and myo-inositol were maintained longer and at a higher level in M. falcata than in M. sativa during cold acclimation at 5 °C. MfMIPS1 transcript was induced by hydrogen peroxide (H2O2) and nitric oxide (NO), but was not responsive to abscisic acid (ABA). Pharmacological experiments revealed that H2O2 and NO are involved in the regulation of MfMIPS1 expression by cold and dehydration, but not by salt. Overexpression of MfMIPS1 in tobacco increased the MIPS activity and levels of myo-inositol, galactinol and raffinose, resulting in enhanced resistance to chilling, drought and salt stresses in transgenic tobacco plants. It is suggested that MfMIPS1 is induced by diverse environmental factors and confers resistance to various abiotic stresses. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction reaction (ENO 3 RR) is a green technology for value-added ammonia production meanwhile treating waste water at ambient conditions. However, it remains a great challenge to construct efficient catalysts due to the complex multiple proton and electron transfer process. Herein, we report a tandem catalyst Cu/Fe 3 O 4 @CN composed of N-doped carbon layer coated Cu/Fe 3 O 4 heterostructure toward highly efficient electrocatalytic nitrate reduction to ammonia production in alkaline medium. The catalyst can achieve an ammonia Faradaic efficiency and ammonia yield rate as high as 96.57 % and 22104.15 μg h -1  mg cat -1 at the optimal potential of -0.9 V vs. RHE in 0.1 M KOH. The outstanding ENO 3 RR performance outperforms the most of reported transitional metal-based ENO 3 RR electrocatalysts. More importantly, Cu/Fe 3 O 4 @CN also exhibits excellent stability even under large current density of 200 mA cm -2 , and long-time durability for continuous electrolysis for 36 h. The experimental and theoretical calculations verify the tandem catalysis mechanism of NO 3 -  → NO 2 -  → NH 3 through the synergism of the two components Cu and Fe 3 O 4 in Cu/Fe 3 O 4 @CN. Specifically, Cu has strong NO 3 - adsorption capacity which can be reduced into NO 2 - , while Fe 3 O 4 can boost water dissociation to generate abundant active *H, ensuring the smooth hydrogenation process while suppressing the occurrence of competitive hydrogen evolution reactions (HER). The heterostructure formation between Cu and Fe 3 O 4 also significantly reduces the energy barrier of the rate-determining step (*NO → *NOH), which results in the high performance of Cu/Fe 3 O 4 @CN., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)