Search Results (6)

Peanut (Arachis hypogaea L.) is one of the most important oilseeds crops worldwide. Through symbiosis with the bacterium Bradyrhizobium sp., peanuts can assimilate atmospheric nitrogen, reducing the need for chemical fertilizers. However, this nitrogen fixation process is highly sensitive to environmental factors that can inhibit the early stages of symbiotic interaction. In this study, we propose the encapsulation of Bradyrhizobium sp. SEMIA6144 and the flavonoid naringin (Nar) in alginate beads to improve flavonoid stability and promote nodulation kinetics in peanuts. Three types of beads were synthesized: A (control, SEMIA6144 only); B (SEMIA6144 induced with 10 µM Nar); and C (SEMIA6144 co-entrapped with 1 mM Nar). Although Nar increased cell mortality (2-fold compared to control) and reduced metabolic activity—particularly at 1 mM—cells in beads B and C responded by altering their membrane fatty acid profile (30% and 55.5% of 18:1, respectively) leading to a reduction in saturated fatty acids (5.8% and 13.1% for 16:0 and 18:0 in B; 11.8% and 21.2% in C). Bacterial release kinetics followed a primarily Fickian diffusion model, with minor matrix–bacteria interactions in Nar-treated beads. Notably, bacterial release in peanut root exudates was 6%, 10%, and 11% higher for beads A, B, and C, respectively, compared to release in physiological solutions. Nar-beads enhanced the formation of curved root hairs, promoted bacterial colonization in root hair zones, and stimulated the appearance of rosette-like structures associated with nodule initiation. In conclusion, encapsulating Bradyrhizobium sp. SEMIA6144 with Nar in beads represents a promising strategy to improve symbiotic nitrogen fixation in peanuts. Full article

Intercropping can enable more efficient resource use and increase yield. Most current studies focus on the correlation between soil nutrients and crop yield under intercropping conditions. However, the mechanisms related to root exudates and soil nutrients remain unclear. Therefore, this study explored the correlation between rhizosphere soil nutrients and root exudates in sugarcane/peanut intercropping. Root extracts, root exudates, rhizosphere soil enzyme activities, and soil nutrients were analyzed and compared in monocultured and intercropped peanut and sugarcane at different growth stages. The root metabolites were annotated using the Kyoto Encyclopedia of Genes and Genomes pathways to further identify the connection between soil nutrients and root exudates. The effects of intercropping differed in peanut and sugarcane at different growth stages, and the difference between podding and pod-filling stages was significant. Intercropping generally had a great effect on peanut; it not only significantly increased the organic acid, soluble sugars, and phenolic acids in root exudates and extracts from peanuts, but also significantly increased rhizosphere soil enzyme activities and soil nutrient levels. Intercropping peanuts promoted fumaric acid secretion from roots and significantly affected the metabolic pathways of alanine, aspartate, and glutamate. Sugarcane/peanut intercropping can increase root exudates and effectively improve soil nutrients. The changes in soil nutrients are closely related to the effects of fumaric acid on alanine, aspartate, and glutamate metabolism. Full article

In this study, cold plasma treatments are employed to modify peanuts. This study systematically investigates the effects of various plasma treatment conditions, including power, duration, and gas type, on the microstructure of peanut seed coats and embryos. Observations under a scanning electron microscope (SEM) reveal that as plasma treatment power increases from 100 W to 500 W, the etching level of peanut seed coats significantly intensifies, surface roughness deepens, and concavities become more pronounced. Additionally, micro-pores on the seed coat gradually enlarge and form cracks. Specifically, when the plasma treatment is set at 200 W for 60 s, the oxygen (O₂) treatment group shows interconnected cracks on the peanut seed coat surface, with lipid particles exuding and protein particles and polymers decomposing. In contrast, the helium (He) treatment group displays clear cell structures and deep grooves, with no noticeable lipid particles exuding around surface cracks. The argon (Ar) treatment group exhibits a distinct rectangular cell structure with clear boundaries, and although surface cracks form, only a few protein particles escape from the cracks. The embryo surface structure becomes looser after plasma treatment, leading to the disintegration of lipid particles, protein particles, and polymers, affecting the fusion and migration of large and small lipid bodies within the peanut’s internal structure. Increasing treatment duration intensifies the etching phenomenon, resulting in more lipid particles exuding, which indicates a positive correlation between lipid particles exuding and treatment duration. This study sheds light on the mechanisms underlying changes in peanut microstructure due to cold plasma treatment, providing scientific evidence for improving peanut quality, enhancing oil extraction efficiency, and optimizing food processing techniques. Full article

Wild peanut species Arachis correntina (A. correntina) had a higher continuous cropping tolerance than peanut cultivars, closely correlating with the regulatory effects of its root exudates on soil microorganisms. To reveal the resistance mechanism of A. correntina to pathogens, we adopted transcriptomic and metabolomics approaches to analyze differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) between A. correntina and peanut cultivar Guihua85 (GH85) under hydroponic conditions. Interaction experiments of peanut root exudates with Ralstonia solanacearum (R. solanacearum) and Fusarium moniliforme (F. moniliforme) were carried out in this study. The result of transcriptome and metabolomics association analysis showed that there were fewer up-regulated DEGs and DEMs in A. correntina compared with GH85, which were closely associated with the metabolism of amino acids and phenolic acids. Root exudates of GH85 had stronger effects on promoting the growth of R. solanacearum and F. moniliforme than those of A. correntina under 1 and 5 percent volume (1% and 5%) of root exudates treatments. Thirty percent volume (30%) of A. correntina and GH85 root exudates significantly inhibited the growth of two pathogens. The exogenous amino acids and phenolic acids influenced R. solanacearum and F. moniliforme showing concentration effects from growth promotion to inhibition as with the root exudates. In conclusion, the greater resilience of A. correntina) to changes in metabolic pathways for amino acids and phenolic acids might aid in the repression of pathogenic bacteria and fungi. Full article

Replant disease significantly hinders the development of the grape industry, and the imbalance of the rhizosphere microecological environment is one of the fundamental reasons hindering grape replants. Peanut is a common intercropping crop, and whether the root exudates of peanut can alleviate grape replant obstacles is still unknown. In this study, the effects of exogenous peanut root exudates on replanting grapevine growth, and the microbial community structure of grapevine replant soils were studied. The results showed that peanut root exudates could promote the growth of replanting grapevine seedlings; enhance root vigor and SOD activity, increasing 55.18% and 95.71%, respectively; and reduce the MDA content of root, decreasing 31.10%. After peanut exudate treatment, the growth of Fusarium solanum, an important harmful fungus that is an obstacle to grape replant, was inhibited. The relative abundances of Gaiella in bacteria and Cystobasidium and Mortierella in fungi increased, and the potential pathogen fungi Fusicolla decreased. Peanut root exudates also modified the soil bacterial and fungal community in a certain range and increased the interaction among the bacteria of grapevine rhizosphere soil. However, they loosened the interaction among fungi. There are extensive mutualistic interactions among bacteria or fungi in grape rhizosphere assemblages after peanut exudates treatment. Therefore, peanut root exudates might be helpful in changing the soil microbial environment and alleviating the grape replanting obstacle. Full article

Cultivation of the peanut (Arachis hypogaea L.) on the same land contributes to the accumulation of root exudates, leading to increased soil pathogens and decreased yield. Trichoderma harzianum is a naturally occurring endophytic biocontrol fungus that can enhance plant growth, nutrient uptake, and tolerance to biotic and abiotic stresses. Separately, Bradyrhizobium spp. is a biological nitrogen-fixing (BNF) bacterium favoring nodule formation in peanut roots which promotes nitrogen fixation. The dynamics of the symbiotic association between these two organisms were evaluated in the laboratory and greenhouse conditions. Peanuts were cultivated in pots inoculated with either Bradyrhizobium or Trichoderma or both to evaluate growth, development, and yield. The in vitro study results showed that seeds treated with Trichoderma had better germination and seedling biomass (p = 0.0008) compared to the other treatments. On the other hand, the results of greenhouse studies showed that seeds inoculated with both microbes, and those inoculated with Bradyrhizobium alone had higher dry biomass (p < 0.0001) as well as higher chlorophyll content (p < 0.0001) compared to the other treatments. Understanding of the interactive effects of fungal endophytes and rhizobial bacteria on plant growth and development will help in both the nutrient and disease management of Arachis hypogaea L. Full article