Preparation of environmental remediation material based on manganese-slag and sewage sludge as a strategy for remediation of cadmium pollution.

Both manganese-slag and sewage sludge are typical solid wastes, but their utilization is limited. Based on the soil properties, the abovementioned pollutants were combined with Broussonetia papyrifera to treat soil cadmium (Cd) pollution. Three materials (sewage sludge-derived biochar (SSB), Mn-SSB, and Mn-slag (Slag)) were prepared using oxygen-limited pyrolysis technology with Slag and sewage sludge, and the effects of the three materials on the phytoremediation of Cd-polluted soil were investigated. All three materials had distinct morphological characteristics, good functional group structure, specific surface area, and porosity. The adsorption and leaching experiments in the solution indicated that the three materials could not only directly absorb Cd2+ but also release nutrients, such as nitrogen and phosphorus. The soil pH increased significantly (p < 0.05) with the addition of the above environmental remediation materials. Furthermore, the contents of soil organic carbon, available nitrogen, and available phosphorus in soil increased significantly, whereas the electrical conductivity of the soil decreased significantly (p < 0.05). During remediation of Cd-polluted soil by integrating the above materials with B. papyrifera, Slag significantly increased the B. papyrifera biomass, but the effects of SSB and Mn-SSB were not significant. SSB, Mn-SSB, and Slag significantly increased the protein content of B. papyrifera leaves, with Mn-SSB having the most significant effect (p < 0.05). The applications of SSB, Mn-SSB, and Slag reduced the malondialdehyde content and increased the activities of superoxide dismutase and peroxidase, reducing the damage to B. papyrifera. Mn-SSB significantly reduced the Cd content in the roots, stems, and leaves of B. papyrifera, and SSB and Slag promoted Cd enrichment in B. papyrifera. This study realized the comprehensive utilization of Mn-slag and sewage sludge and established a recycling system from solid waste to the treatment of waste soil.

Integrative Metabolome and Transcriptome Analysis of Flavonoid Biosynthesis Genes in Broussonetia papyrifera Leaves From the Perspective of Sex Differentiation.

Flavonoids are important secondary metabolites involved in plant development and environmental responses. Sex differences in flavonoids are common in plants. Broussonetia papyrifera is a dioecious plant that is rich in flavonoids. However, few studies have been done on its molecular mechanism, especially sex differences. In the present study, we performed an integrated transcriptomics and metabolomics analysis of the sex differences in the accumulation of flavonoids in B. papyrifera leaves at different developmental stages. In general, flavonoids accumulated gradually with developmental time, and the content in female plants was higher than that in male plants. The composition of flavonoids in female and male plants was similar, and 16 kinds of flavonoids accumulated after flowering. Correspondingly, a significant enrichment of differentially expressed genes and metabolites was observed in the flavonoid biosynthesis pathway. WGCNA and qRT-PCR analyses identified several key genes regulating the accumulation of flavonoids, such as those encoding CHS, CHI and DFR. In addition, 8 TFs were found to regulate flavonoid biosynthesis by promoting the expression of multiple structural genes. These findings provide insight into flavonoid biosynthesis in B. papyrifera associated molecular regulation.