We have prepared four isomeric binuclear ruthenium complexes, in which two ruthenium units have been attached to the 1,4-(4a), 1,5-(4b), 1,8-(4c), or 2,6-positions (4d) of a central anthraquinone (Aq) moiety, leading to packed (4c) or extended (4a,b,d) topologies. All of these bimetallic complexes were fully characterized by elemental analysis, 1 H, 13 C{ 1 H}, and 31 P NMR{ 1 H} spectrometry, and UV/vis spectrophotometry. Moreover, the structures of 4a,b were established by X-ray crystallography. The electrochemical properties of the stable binuclear ruthenium complexes 4aÀd were investigated, revealing that the two metal centers in 4aÀc could interact with each other through an anthraquinone bridge, suggesting that the electron-withdrawing carbonyl chain actually functions as an effective bridge.

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Soil water repellency (SWR) is a physical phenomenon whereby water cannot penetrate or has difficulty penetrating the soil surface. There are many factors involved in its occurrence, but the main factors controlling its emergence in loess remain unclear. In this work, we have studied numerous physicochemical and biological factors functioning in different dominant vegetations (Pinus tabulaeformis Carr., Robinia pseudoacacia L., and Hippophae rhamnoides L.) in a loess hilly region by gas chromatography–mass spectrometry (GC-MS) and high-throughput sequencing techniques. We observed that more than 75% of the soils under Robinia and Hippophae are categorized as slightly or strongly water repellent, while nearly 50% of the soils under Pinus are categorized as severely to extremely water repellent. The relative concentrations of total free lipids in the soil in the same water-repellency class were Pinus > Robinia > Hippophae, where fatty acids, alkanols, and sterols were positively correlated with SWR, whereas alkanes were not. For the abundance and diversity index of bacterial and fungal communities, the three species ranked in the following order: Robinia ≈ Hippophae > Pinus. Thus, solvent-extractable polar waxes were indicated to be better preserved in water-repellent soils under Pinus due to lower microbial diversity than Robinia and Hippophae. Here, we demonstrate polar waxes to be the principal factor controlling SWR. Moreover, the dominant phyla of fungi varied greatly than those of bacteria under three vegetation types. Correlation analysis showed that the abundance of Actinobacteria in dominant bacteria increased with SWR. Nonmetric multidimensional scaling suggested the fungal community in different water-repellent soils under Pinus to vary more than those under Robinia and Hippophae. The indicator species mainly belonged to Actinobacteria in bacteria and Basidiomycota in fungi at the phylum level; this finding was further supported by the linear discriminant analysis (LDA) effect size (LEfSe). Additionally, GC-MS identified a small amount of ergosterol, a specific biomarker of fungi under Pinus. These pieces of evidence collectively reveal that severe to extreme SWR occurs under Pinus and appears to be the most influenced by fungi and actinomycetes when the topsoil is close to air drying. However, there is a need for further testing on different plant species or land use.

Glucosinolates (GLS) are important anionic secondary metabolites that are rich in thiocyanin in cabbage, Brassica oleracea L. var. capitata. GLS are important in food flavor, plant antimicrobial activity, insect resistance, disease resistance, and human anti-cancer effects. Sulfur is an important raw material of GLS, directly affecting their synthesis. However, the mechanism of sulfur regulation of GLS biosynthesis in cabbage is unclear. In the present study, cabbage was treated with sulfur-free Hoagland nutrient solution (control; −S), and normal Hoagland nutrient solution (treatment; +S). Through joint transcriptomic and proteomic analyses, the effect of exogenous S on GLS synthesis was explored. S application induced GLS accumulation; especially, indole glycosides. Transcriptome analysis showed that +S treatment correlated positively with differentially expressed genes and proteins involved in amino acid biosynthesis, carbon metabolism, and plant hormone signal transduction. Compared with −S treatment, the mRNA expression of GLS synthesis genes (CYP, GSTU, UGT, and FMO) and those encoding transcription factors (RLK, MYB, AP2, bHLH, AUX/IAA, and WRKY) were upregulated significantly in the +S group. Combined transcriptome and proteome analysis suggested that the main pathway influenced by S during GLS synthesis in cabbage is amino acid biosynthesis. Moreover, S treatment activated GLS synthesis and accumulation.

Background and aims It is widely accepted that soil water repellency (SWR) is mainly caused by plant-derived hydrophobic compounds in soils. The relation between these hydrophobic compounds, which are defined as SWR biomarkers, and SWR has been rarely known and the knowledge of their sources remains controversial. We aimed to select key SWR biomarkers predicting SWR and to trace their origin. Methods Topsoils under/around five dominant plant species (DPS) belonging to various plant functional types (PFTs) on the Chinese Loess Plateau were sampled, together with plant samples, i.e., plant leaves and roots. A sequential extraction procedure and hydrolysis approach was applied to obtain three organic fractions: dichloromethane (DCM)/MeOH soluble fraction (D), DCM/MeOH soluble fraction of isopropanol/ammonia solution (IPA/NH3) extract (AS), and DCM/MeOH insoluble fraction of IPA/NH3 extract (AI), which were analyzed by gas chromatography-mass spectrometry. Results The two-way hierarchical clustering analysis revealed a distinct division of soil organic carbon composition under different DPS, and the leaves of evergreen trees offered more cutin than those of other PFTs. In addition, structural equation modeling showed that AS cutin (path coefficient = 0.30) and AI cutin (path coefficient = 0.47) had direct and positive effects on SWR. Moreover, there was a strong link between SWR and the ratio of the two separate compound groups when AS cutin or AI cutin were taken as the numerators. Conclusion After considering the SWR behavior during extraction and the chemical composition of each fraction, we concluded that leaf-derived cutin appears to have the greatest effect.