1. Crop diversity management is widely used to increase agricultural productivity and sustainability. Recent studies have demonstrated that maize root exudates can drive interspecific facilitation to enhance N 2 fixation of bean in intercropping systems. However, the mechanisms of N 2 fixation enhancement stimulated by root exudates in the intercropping systems remain unclear.2. Four experiments were designed to provide a progressively deeper understanding of how root exudates stimulate microbial-mediated N 2 fixation. First, the effects of faba bean/maize intercropping on yields and soil microbial communities were determined in a field experiment. Second, root-derived interspecific facilitation was evaluated using a root partitioning approach. Third, the key microbial taxa in the faba bean rhizosphere were traced using 13 C-labelled maize root exudates.Fourth, the co-driven mechanism of maize root exudates and micro-organisms in the faba bean rhizosphere were explored.3. Faba bean/maize intercropping with maize residue return increased the yields of faba bean (26%), maize (27%) and broccoli (9.1%) compared to that under monocropping. Nodulin-like 4 (NODL4), chalcone-flavanone isomerase (CFI) and early nodulin-like (ENODL2) gene expression in faba bean roots intercropped with maize increased by 1.5-2.3-fold compared to that observed under monoculture.More than half of the N 2 fixation of faba bean increase under intercropping was due to interactions with micro-organisms. Nine key bacterial genera in the faba bean rhizosphere were identified by 13 C-DNA-based stable isotope probing analysis. Among them Agromyces, Arthrobacter, Bacillus, Lysobacter and Paenibacillus directly fix N 2 , while Gemmatimonas, Heliobacillus, Natronocella and Sorangium increase the N 2 fixation capacity of Azotobacter by providing additional carbon sources. These key bacteria triggered by maize root exudates played an important role in the rhizosphere facilitation of intercropping.

No abstract

No abstract

Oral squamous cell carcinoma (OSCC) is a malignant neoplasm with high mortality and morbidity. The role of circRNA and its molecular mechanism in OSCC remains largely unknown. The study aims to explore the role of a novel circular RNA (circLDLRAD3) in OSCC and its underlying mechanism. PCR and fluorescence in situ hybridization were used to explore the expression features of circLDLRAD3 in OSCC. The effects of circLDLRAD3 on the behaviour of OSCC were investigated using CCK‐8, colony formation assay, transwell and animal experiments. Bioinformatics analysis along with dual luciferase reporter assay and RIP assay were used to reveal the interaction between circLDLRAD3, miR‐558 and Smad4. It was revealed that circLDLRAD3 exhibited low expression status in OSCC. CircLDLRAD3 inhibits proliferation, migration, and invasion of OSCC cells both in vitro and in vivo. Mechanistically, circLDLRAD3 could bind with miR‐558 to positively regulate its target gene Smad4 expression. Rescue experiments further confirmed both miR‐558 overexpression and Smad4 knockdown could reverse the influence of circLDLRAD3 on OSCC phenotypes. Moreover, circLDLRAD3 regulate the TGF‐β signalling pathways to influence EMT through miR‐558/Smad4 axis. Our study found that circLDLRAD3 is downregulated in OSCC and verified its tumour suppressor function and mechanism in OSCC through sponging miR‐558 to regulate miR‐558/Smad4/TGF‐β axis. The characterization of such regulating network uncovers an important mechanism underlying OSCC progression, which could provide promising targets targeted therapy strategies for OSCC in the future.