Mercury is one of the most toxic pollutants that has drawn the attention of scientists. This study investigates the phytoremediation capabilities of Vigna radiata L. in conjunction with microbial biostimulators. The inoculated seeds were cultivated in soil under controlled greenhouse conditions. The concentration of Hg, biomass, and photosynthetic pigments was investigated under amendment factor including EDTA, bacterial, fungal (Mycorrhiza and Trichoderma), biochar, and combined levels, as well as the pollution factor with three levels of HgCl2 as two factorial experiments. Results showed that Plant Growth-Promoting Microorganisms (PGPMs) influenced mercury absorption and distribution in different plant organs. Aside from biochar, all stimulators increased the plant\'s Hg concentration. Although EDTA greatly increased mercury accumulation in plants, it reduced biomass. Fungal and bacterial treatments increased total mercury in the plant but decreased its concentration in the leaves. The combination of bacteria and fungi resulted in the highest mercury absorption, while the biochar in combination with PGPMs produced the greatest biomass. Analysis of mercury concentration in seeds indicated that V radiata effectively prevented its contamination in seeds. The results disclosed that microbial combinations of bacteria and fungi could increase the plant\'s potential to cope with heavy metal pollution. This improvement is due to the different roles of these two organisms, like nitrogen fixation by bacteria and phosphorus absorption by mycorrhiza fungi. Moreover, biochar as a soil amendment and microorganism carrier was noticed. Finally, considering the plant\'s inherent capacity to stabilize mercury in the roots, phytostabilization with the benefit of combined levels of biochar and microorganisms can be introduced as the best approach.

The physiological activity facilitated by arbuscular mycorrhizal fungi (AMF) contributes to plants\' ability to tolerate drought. Nevertheless, it is unclear if AMF colonization affects the expression of genes in the host plant that encode antioxidant enzymes in the superoxide dismutase (SOD) family, which help alleviate drought stress in plants. Here, we conducted a pot trial to determine whether colonization by the AMF Rhizophagus irregularis improves drought resistance in Bombax ceiba. We comprehensively analyzed the SOD gene family and evaluated genome-wide expression patterns of SODs and SOD activity in AMF-colonized and non-mycorrhizal plants under simulated drought. We identified a total of 13 SODs in the genome of B. ceiba, including three FeSODs (BcFSDs), three MnSODs (BcMSDs), and seven Cu/ZnSODs (BcCSDs). Phylogenetic analysis based on binding domain revealed that SOD genes from B. ceiba and various other plant species can be divided into three separate groups, showing significant bootstrap values. Our examination of gene composition and patterns suggests that most BcSOD genes in these three subgroups are significantly conserved. Additionally, it was noted that hormones and stress-responsive cis-regulatory elements were found in all BcSOD promoters. Expression profiling by qRT-PCR demonstrated that AMF increased relative expression levels of Cu/Zn-SODs in both roots and shoots under drought stress, except for BcCSD3 in roots. Furthermore, AMF colonization increased the relative expression of BcMSD1a and BcMSD1b in roots, augmenting SOD activities and increasing ROS scavenging during drought. In general, this work offers molecular evidence in support of the beneficial effect of AMF colonization on drought tolerance in B. ceiba. It also elucidates the expression patterns of SOD genes, which will support efforts to optimize mycorrhizal seedling cultivation under stressful conditions.

BACKGROUND: Soybean is the main oil crop in Northeast China. Continuous monocropping is more commonly used for soybean production due to rising market demand and arable land constraints. However, autotoxic substances, such as phenolic acids, produced by continuously cropped soybean can reduce yield and quality. The mycorrhiza formed of Arbuscular mycorrhizal fungi (AMF) and plant roots regulate the metabolic activities of the host plant and increase its disease resistance. The main purpose of this study was to inhibit the production of phenolic acids and determine the adverse effects on the growth of continuous monocropping soybean by inoculating Funneliformis mosseae (F. mosseae).
RESULTS: Transcriptomics results showed that the production of phenolic acids in continuous monocropping soybean roots was mainly regulated by the expression of the CHS6, PCL1, SAMT, SRG1, and ACO1 genes, and the expression of these genes was significantly downregulated after inoculation with F. mosseae. Metabolomics results showed that continuous monocropping soybean roots inoculated with F. mosseae inhibited phenolic acid production through the phenylpropane biosynthetic, α-linoleic acid, linoleic acid, and other metabolic pathways. Phenolic acids in the phenylpropane metabolic pathway, such as 4-hydroxybenzoic acid, phthalic acid, and vanillic acid, decreased significantly after inoculation with F. mosseae. The combined analysis of the two showed that genes such as YLS9 and ARF3 were positively correlated with 4-hydroxybenzoic acid and so on, while genes such as CHS6 and SRG1 were negatively correlated with butyric acid and so on.
CONCLUSIONS: F. mosseae regulated the expression of functional genes and related phenolic acid metabolic pathways produced by continuous monocropping soybean roots, inhibiting the production of phenolic acid autotoxic substances in continuous cropped soybean, and slowing down the disturbance of continuous monocropping. This study provides a new solution for continuous monocropping of plants to overcome the autotoxicity barrier and provides a new basis for the development and utilization of AMF as a biological agent.

Although the effects of plants on soil properties are well known, the effects of distance from plant roots to root-free soil on soil properties and associated soil organisms are much less studied. Previous research on the effects of distance from a plant explored specific soil organisms and properties, however, comparative studies across a wide range of plant-associated organisms and multiple model systems are lacking. We conducted a controlled greenhouse experiment using soil from two contrasting habitats. Within each soil type, we cultivated two plant species, individually and in combination, studying soil organisms and properties in the root centre, the root periphery, and the root-free zones. We showed that the distance from the cultivated plant (representing decreasing amount of plant roots) had a significant impact on the abiotic properties of the soil (pH and available P and N) and also on the composition of the fungal, bacterial, and nematode communities. The specific patterns, however, did not always match our expectations. For example, there was no significant relationship between the abundance of fungal pathogens and the distance from the cultivated plant compared to a strong decrease in the abundance of arbuscular mycorrhizal fungi. Changes in soil chemistry along the distance from the cultivated plant were probably one of the important drivers that affected bacterial communities. The abundance of nematodes also decreased with distance from the cultivated plant, and the rate of their responses reflected the distribution of their food sources. The patterns of soil changes along the gradient from plant to root-free soil were largely similar in two contrasting soil types and four plant species or their mixtures. This suggests that our results can be generalised to other systems and contribute to a better understanding of the mechanisms of soil legacy formation.

Entisol soil is hard and compact in nature, rendering it high in bulk density, which influences root penetration adversely and thereby poor plant growth. In this experiment, used seven treatments in different combination in normal soil, were used as growth media for the Terminalia arjuna seedling. T3 (60% entisol) found the best as it gave the highest biomass in the species regardless of arbuscular mycorrhizal fungi (AMF) treatment. AMF treatment enhanced the growth and biomass of plants significantly in all the given treatments. AMF colonization observed a maximum in tertiary roots. T1 (100% entisol soil) exhibited the highest degree of AMF colonization in tertiary roots, resulting in the highest mycorrhiza dependency of plants for this soil. The addition of normal soil to entisol soil was found to decrease the bulk density, resulting in increased root diameter, and T3 plants exhibited the highest biomass and AMF compatibility for T. arjuna species. The T. arjuna plant\'s growth and biomass responded positively to AMF in all types of treatments. The plant\'s growth and biomass were highest in the T3 treatment, which had a bulk density of 1.50 g/cm3. In this study, we combined the entisol with mycorrhizal inoculation of the nursery growing medium to promote plant growth and biomass, improve the plant\'s ability to hold water and absorb nutrients, and lower the entisol\'s bulk density. The T. arjuna (Roxb) plant responds very favorably to mycorrhiza inoculation in nursery conditions with the entisol growth medium.

UNASSIGNED: Maize/soybean intercropping is a common cropping practice in Chinese agriculture, known to boost crop yield and enhance soil fertility. However, the role of below-ground interactions, particularly root exudates, in maintaining intercropping advantages in soybean/maize intercropping systems remains unclear.
UNASSIGNED: This study aimed to investigate the differences in root exudates between intercropping and monocropping systems through two pot experiments using metabolomics methods. Multiple omics analyses were conducted to explore correlations between differential metabolites and the community of Arbuscular Mycorrhizal Fungi (AMF), shedding light on the mechanisms underlying the dominance of intercropping from the perspective of root exudates-soil microorganism interactions.
UNASSIGNED: The study revealed that intercropping significantly increased the types and contents of root exudates, lowered soil pH, increased the availability of nutrients like available nitrogen (AN) and available phosphorus (AP), and enhanced AMF colonization, resulting in improving the community composition of AMF. Besides, root exudates in intercropping systems differed significantly from those in monocropping, with 41 and 39 differential metabolites identified in the root exudates of soybean/maize, predominantly amino acids and organic acids. The total amount of amino acids in the root exudates of soybean intercropping was 3.61 times higher than in monocropping. Additionally, the addition of root exudates significantly improved the growth of soybean/maize and AMF colonization, with the mycorrhizal colonization rate in intercropping increased by 105.99% and 111.18% compared to monocropping, respectively. The identified metabolic pathways associated with root exudates were closely linked to plant growth, soil fertility improvement, and the formation of AMF. Correlation analysis revealed a significant relationship (P < 0.05) between certain metabolites such as tartaric acid, oxalic acid, malic acid, aspartic acid, alanine, and the AMF community. Notably, the photosynthetic carbon fixation pathway involving aspartic acid showed a strong association with the function of Glomus_f_Glomerace, the dominant genus of AMF. A combined analysis of metabolomics and high throughput sequencing revealed that the root exudates of soybean/maize intercropping have direct or indirect connections with AMF and soil nutrients.
UNASSIGNED: This suggests that the increased root exudates of the soybean/maize intercropping system mediate an improvement in AMF community composition, thereby influencing soil fertility and maintaining the advantage of intercropping.

Arbuscular mycorrhizal inoculation can promote plant growth, but specific research on the difference in the symbiosis effect of arbuscular mycorrhizal fungi and plant combination is not yet in-depth. Therefore, this study selected Medicago sativa L., Bromus inermis Leyss, and Festuca arundinacea Schreb., which were commonly used for restoring degraded land in China to inoculate with three AMF separately, to explore the effects of different AMF inoculation on the growth performance and nutrient absorption of different plants and to provide a scientific basis for the research and development of the combination of mycorrhiza and plants. We set up four treatments with inoculation Entrophospora etunicata (EE), Funneliformis mosseae (FM), Rhizophagus intraradices (RI), and non-inoculation. The main research findings are as follows: the three AMF formed a good symbiotic relationship with the three grassland plants, with RI and FM having more significant inoculation effects on plant height, biomass, and tiller number. Compared with C, the aboveground biomass of Medicago sativa L., Bromus inermis Leyss, and Festuca arundinacea Schreb. inoculated with AMF increased by 101.30-174.29%, 51.67-74.14%, and 110.67-174.67%. AMF inoculation enhanced the plant uptake of N, P, and K, and plant P and K contents were significantly correlated with plant biomass. PLS-PM analyses of three plants all showed that AMF inoculation increased plant nutrient uptake and then increased aboveground biomass and underground biomass by increasing plant height and root tillering. This study showed that RI was a more suitable AMF for combination with grassland degradation restoration grass species and proposed the potential mechanism of AMF-plant symbiosis to increase yield.

UNASSIGNED: Ferns constitute the second largest group of vascular plants. Previous studies have shown that the diversity and composition of fern communities are influenced by resource availability and water stress, among other factors. However, little is known about the influence of these environmental factors on their biotic interactions, especially regarding the relationship between mycorrhizal fungi and ferns. The present study compares the mycorrhizal communities associated with 36 populations of Struthiopteris spicant L. Weiss across Europe and North America. This species exhibits a great tolerance to variations in light, nutrient, and pH conditions, and it can survive with and without mycorrhizae.
UNASSIGNED: With the aim of determining which environmental factors impact the composition and abundance of the root-associated fungal communities in this species, we used an ITS-focused metabarcoding approach to identify the mycorrhizal fungi present and analyzed the influence of climatic and edaphic variables at global and regional scales.
UNASSIGNED: We encountered striking differences in the relative abundance of arbuscular mycorrhizal fungi (AMF) between S. spicant populations at both spatial levels. We recorded a total of 902 fungal ASVs, but only 2- 4% of the total fungal diversity was observed in each individual, revealing that each fern had a unique fungal community. Light availability and the interactive action of pH and soil nitrogen concentration showed a positive influence on AMF relative abundance, explaining 89% of the variance. However, environmental factors could only explain 4- 8% of the variability in AMF community composition, indicating that it might be determined by stochastic processes. These results support the hypothesis that ferns may be more independent of mycorrhization than other plant groups and interact with fungi in a more opportunistic manner.

The Transporter 1/Peptide Transporter Family (NPF) is essential for the uptake and transport of nitrate nitrogen. Significant increases in nitrogen have been increasingly reported for many mycorrhizal plants, but there are few reports on maize. Here, we have identified the maize NPF family and screened for arbuscular mycorrhiza fungi (AMF) induced NPFs. In this study, a systematic analysis of the maize NPF gene family was performed. A total of 82 NPF genes were identified in maize. ZmNPF4.5 was strongly induced by AMF in both low and high nitrogen. Lotus japonicus hairy root-induced transformation experiments showed that ZmNPF4.5 promoter-driven GUS activity was restricted to cells containing tufts. Yeast backfill experiments indicate that ZmNPF4.5 functions in nitrate uptake. Therefore, we speculate that ZmNPF4.5 is a key gene for nitrate-nitrogen uptake in maize through the mycorrhizal pathway. This is a reference value for further exploring the acquisition of nitrate-nitrogen by maize through AMF pathway.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s12298-024-01464-3.

Solanum nigrum is a common weed in arable land, while being used in traditional medicine around the world due to its remarkable levels of valuable secondary metabolites. Agronomic and biological techniques can alter the production of a specific metabolite by influencing plant growth and metabolism. The effects of colonization with three arbuscular mycorrhizal fungi (AMF), including Funneliformis mosseae, Rhizoglomus intraradices, and Rhizoglomus fasciculatum, on the chemical composition of S. nigrum fruits were evaluated by gas chromatography-mass spectrometry (GC-MS) analysis. More than 100 different chemical constituents were evaluated by GC-MS. Our study revealed that the levels of phenols (quinic acid), benzenes (hydroquinone), sulfur-containing compounds, lactone and carboxylic acids were improved by R. intraradices. In contrast, hydroxymethylfurfural increased by 68 % in R. fasciculatum inoculated with uninoculated S. nigrum plants, and this species was also the most efficient in inducing sugar compounds (D-galactose, lactose, and melezitose). Our results suggest that AMF colonization is an effective biological strategy that can alter the chemical composition and improve the medicinal properties of S. nigrum.