Cadmium (Cd) and arsenic (As) contamination of soil has been a public concern due to their potential accumulation risk through the food chain. This study was conducted to investigate the performance of ferrous sulfate (FeSO₄) and ferric oxide (Fe₂O₃) nanoparticle (Nano-Fe) to stabilize the concentrations of Cd and As in paddy soil. Both Fe treatments led to low extractable Cd and the contents of specifically sorbed As contents, increased (p < 0.05) the Shannon index and decreased (p < 0.05) the Simpson diversity indices compared with the control. Nano-Fe increased the relative abundances of Firmicutes and Proteobacteria and decreased the abundances of Acidobacteria and Chloroflexi. Moreover, the addition of both forms of Fe promoted the formation of Fe plaque and decreased the translocation factor index (TFs) _root/soil, TFs _shoot/root, and TFs _grain/shoot of Cd and As. These results suggest that exogenous Fe may modify the microbial community and decrease the soil available Cd and As contents, inhibit the absorption of Cd and As by the roots and decrease the transport of Cd and As in rice grains and the risk intake in humans. These findings demonstrate that soil amendment with exogenous Fe, particularly Nano-Fe, is a potential approach to simultaneously remediate the accumulation of Cd and As from the soil to rice grain systems.

Selenium (Se) is an essential trace element for humans. Arbuscular mycorrhizal fungi (AMF) play a crucial role in increasing plant micronutrient acquisition. Soybean (Glycine max (Linn.) Merr.) is a staple food for most people around the world and a source of Se. Therefore, it is necessary to study the mechanism of Se intake in soybean under the influence of AMF. In this study, the effects of fertilization with selenite and inoculation with different AMF strains (Claroideoglomus etunicatum (Ce), Funneliformis mosseae (Fm)) on the accumulation and speciation of Se in common soybean plants were discussed. We carried out a pot experiment at the soil for 90 days to investigate the impact of fertilization with selenite and inoculation with Ce and Fm on the Se fractions in soil, soybean biomass, accumulation and speciation of Se in common soybean plants. The daily dietary intake of the Se (DDI) formula was used to estimate the risk threshold of human intake of Se from soybean seeds. The results showed that combined use of both AMF and Se fertilizer could boost total Se and organic Se amounts in soyabean seeds than that of single Se application and that it could increase the proportion of available Se in soil. Soybean inoculated with Fm and grown in soil fertilized with selenite had the highest organic Se. The results suggest that AMF inoculation could promote root growth, more soil water-soluble Se and higher Se uptake. The maximum Se intake of soybean for adults was 93.15 μg/d when treated with Se fertilizer and Fm, which satisfies the needs of Se intake recommended by the WHO. Combined use of AMF inoculation and Se fertilizer increases the bioavailable Se in soil and promotes the total Se concentration and organic Se accumulation in soybean. In conclusion, AMF inoculation combined with Se fertilization can be a promising strategy for Se biofortification in soybean.

Manganese toxicity severely restricts the growth and yield of sugarcane in acidic soil. However, the molecular mechanism of the specific tolerance of different genotypes to manganese remains unclear. This study aims to identify and functionally characterize the ZIP manganese transporter genes in sugarcane, and to elucidate the differences in manganese regulatory mechanisms between the sensitive type GT32 (Saccharum hybrid cultivar) and the tolerant type ZZ1 (Saccharum hybrid cultivar). Through phylogenetic analysis, conserved motifs and cis-acting element analysis, as well as Ka/Ks analysis, a total of 24 ZIP genes were identified in three different sugarcane genotypes. Combined with hydroponic manganese stress treatments, quantitative reverse transcription PCR (qRT-PCR), ion concentration measurements and chlorophyll analysis, physiological and transcriptional differences between ZZ1 and GT32 were compared. Yeast complementation experiments verified the manganese transport ability of ScIRT1 and ScZIP3. Under manganese stress conditions, the results showed that the chlorophyll content of ZZ1 was 41.14% higher than that of GT32, and the manganese accumulation in roots and stems was lower. Significant differences were also observed in the transcriptional patterns of ZIP genes in roots and stems. The qRT-PCR results indicated tissue-specific differences: the transcription level of ScZIP7 in the roots of GT32 was 10 times higher, while ZZ1 maintained the high transcription level of ScZIP3 under manganese stress. The genotype-dependent expression patterns of ScIRT1, ScZIP3, ScZIP6, and ScZIP7 may contribute to the regulation of manganese uptake and intracellular distribution, thereby contributing to the enhanced manganese tolerance observed in ZZ1. These findings provide valuable insights into the molecular basis of manganese tolerance and highlight potential candidate genes for the genetic improvement in manganese-tolerant sugarcane varieties.