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Nyctinastic leaf movement of Fabaceae is driven by the tiny motor organ pulvinus located at the base of the leaf or leaflet. Despite the increased understanding of the essential role of ELONGATED PETIOLULE1 (ELP1)/PETIOLE LIKE PULVINUS (PLP) orthologs in determining pulvinus identity in legumes, key regulatory components and molecular mechanisms underlying this movement remain largely unclear. Here, we used WT pulvinus and the equivalent tissue in the elp1 mutant to carry out transcriptome and proteome experiments. The omics data indicated that there are multiple cell biological processes altered at the gene expression and protein abundance level during the pulvinus development. In addition, comparative analysis of different leaf tissues provided clues to illuminate the possible common primordium between pulvinus and petiole, as well as the function of ELP1. Furthermore, the auxin pathway, cell wall composition and chloroplast distribution were altered in elp1 mutants, verifying their important roles in pulvinus development. This study provides a comprehensive insight into the motor organ of the model legume Medicago truncatula and further supplies a rich dataset to facilitate the identification of novel players involved in nyctinastic movement.

Exploring advanced electrocatalysts for the sluggish oxygen reduction reaction is extremely important for fuel cell commercialization but still remains a great challenge, especially the durability issue that gains increasing attention. Herein, we demonstrate an extremely durable catalyst prototype that combines structurally ordered intermetallic nanoparticles (NPs) with mesoporous carbon. With ZIF-8 derived mesoporous carbon supported Pt3Co intermetallic NPs (Pt3Co/DMC-F) as an example, we illustrate its synthetic details, electrocatalytic performance and durability enhancement mechanism. The Pt3Co/DMC-F catalyst exhibited significant enhancement in activity and durability. More importantly, its extraordinary performance was observed/verified in a H2/air PEM single cell test. The confinement of mesoporous carbon not only efficiently controls the particle size of Pt3Co and hampers their aggregation during thermal annealing and electrochemical reactions, but also significantly suppresses detachment. Beyond offering an advanced electrocatalyst, this study provides a solution to the durability issue of cathodes that has prevented practical application of proton exchange membrane fuel cells.

Highlights All the important single-atom catalysts (SACs) synthetic strategies, such as wet-chemistry method, atomic layer deposition, metal–organic framework-derived method, electrodeposition, high-temperature atom trapping from bulk particles, and vacancies/defects immobilized strategy, have been summarized and discussed in detail.Various metal-based (especially Pt, Pd, Ru, Fe, Co, Ni, Mo, W, V) SACs in electrocatalytic hydrogen evolution reaction (HER) have been systematically reviewed.The current key challenges in SACs for electrochemical HER are pointed out, and some potential strategies/perspectives are proposed., Hydrogen, a renewable and outstanding energy carrier with zero carbon dioxide emission, is regarded as the best alternative to fossil fuels. The most preferred route to large-scale production of hydrogen is by water electrolysis from the intermittent sources (e.g., wind, solar, hydro, and tidal energy). However, the efficiency of water electrolysis is very much dependent on the activity of electrocatalysts. Thus, designing high-effective, stable, and cheap materials for hydrogen evolution reaction (HER) could have a substantial impact on renewable energy technologies. Recently, single-atom catalysts (SACs) have emerged as a new frontier in catalysis science, because SACs have maximum atom-utilization efficiency and excellent catalytic reaction activity. Various synthesis methods and analytical techniques have been adopted to prepare and characterize these SACs. In this review, we discuss recent progress on SACs synthesis, characterization methods, and their catalytic applications. Particularly, we highlight their unique electrochemical characteristics toward HER. Finally, the current key challenges in SACs for HER are pointed out and some potential directions are proposed as well.

In this work, a glucose-derived carbon supported CrN composite is prepared by using a hydrothermal method and followed by a nitridating process. It is found that CrN nanoparticles in the composite are well-dispersed and separated by the carbon support. More importantly, the composite exhibits significantly enhanced oxygen reduction reaction activity than free-standing aggregated CrN nanoparticles, especially in acidic medium. The onset potential of the composite reaches 0.81 V in acidic medium, which is one of the highest values among the reported metal nitrides. The rotating ring disk electrode results indicate that the composite is more beneficial to O2 dissociation than free-standing CrN nanoparticles. Results of X-ray photoelectron spectroscopy, O2 temperature-programmed desorption and electrochemical impedance spectroscopy indicate that the significantly enhanced oxygen reduction reaction activity of the composite over free-standing CrN is derived not from the new formed active sites or enhanced oxygen adsorption but from the much enhanced electron transfer rate. This observation helps to understand the role of electron transfer rate playing in the oxygen reduction reaction activity of metal nitrides.

Plant height is a vital agronomic trait that greatly determines crop yields because of the close relationship between plant height and lodging resistance. Legumes play a unique role in the worldwide agriculture, however, little attention has been given to the molecular basis of their height. Here, we characterized the first dwarf mutant mini plant 1 (mnp1) of the model legume plant Medicago truncatula. Our study found that both cell length and the cell number of internodes were reduced in a mnp1 mutant. Using the forward genetic screening and subsequent whole-genome resequencing approach, we cloned the MNP1 gene and found that it encodes a putative copalyl diphosphate synthase (CPS) implicated in the first step of gibberellin (GA) biosynthesis. MNP1 was highly homologous to Pisum sativum LS. The subcellular localization showed that MNP1 was located in the chloroplast. Further analysis indicated that GA3 could significantly restore the plant height of mnp1-1, and expression of MNP1 in a cps1 mutant of Arabidopsis partially rescued its mini-plant phenotype, indicating the conservation function of MNP1 in GA biosynthesis. Our results provide valuable information for understanding the genetic regulation of plant height in M. truncatula.

Highly active catalyst for the hydrogen oxidation/evolution reactions (HOR and HER) plays an essential role for the water-to-hydrogen reversible conversion. Currently, increasing attention has been concentrated on developing low-cost, high-activity, and long-life catalytic materials, especially for acid media due to the promise of proton exchange membrane (PEM)-based electrolyzers and polymer electrolyte fuel cells. Although non-precious-metal phosphide (NPMP) catalysts have been widely researched, their electrocatalytic activity toward HER is still not satisfactory compared to that of Pt catalysts. Herein, a series of precious-metal phosphides (PMPs) supported on graphene (rGO), including IrP2-rGO, Rh2P-rGO, RuP-rGO, and Pd3P-rGO, are prepared by a simple, facile, eco-friendly, and scalable approach. As an example, the resultant IrP2-rGO displays better HER electrocatalytic performance and longer durability than the benchmark materials of commercial Pt/C under acidic, neutral, and basic electrolytes. To attain a current density of 10 mA cm-2, IrP2-rGO shows overpotentials of 8, 51, and 13 mV in 0.5 M dilute sulfuric acid, 1.0 M phosphate-buffered saline (PBS), and 1.0 M potassium hydroxide solutions, respectively. Additionally, IrP2-rGO also exhibits exceptional HOR performance in the 0.1 M HClO4 medium. Therefore, this work offers a vital addition to the development of a number of PMPs with excellent activity toward HOR and HER.