Zhongyi Yang

Tailings residual trace elements (TEs) pollution challenges agricultural soils, but their impacts on soil and microbial communities, and economic value are poorly understood. This study explores the potential for TEs re-mining and evaluates microbial community in abandoned mine tailings. Sixty samples were collected from two soil layers (0–15 cm and 15–30 cm) across five sites: 1.5 years (1.5-Y), 7 years (7-Y), 10 years (10-Y), 14 years (14-Y), and an unmined control (CK). TEs contents were quantified using inductively coupled plasma mass spectrometry, while bacterial and fungal communities were characterized via 16 S rRNA and ITS gene sequencing. Total TEs (Ba, Cr, Cs, Ga, Hf, Nb, Rb, Sn, Sr, Ta, Th, Zr, U, V, W, and Y) content ranged from 1617.09–3193.21 µ g g ⁻¹ (CK, 3193.2 µ g g ⁻¹ > 14-Y, 2234.22 µ g g ⁻¹ > 10-Y, 1986.94 µ g g ⁻¹ > 7-Y, 1827.29 µ g g ⁻¹ > 1.5-Y, 1617.09 µ g g ⁻¹ ). Residual TEs ratios varied from 21.91% to 65.51%, with extraction ultimate values of 1.098 (Ga) to 3.032 (Y) and initial ore value ratios of 0.280 (Cs) to 0.795 (Sr). The phyto-remining potential index (PRPI) spanned 0.358 (Cs) to 2.316 (Y), with a threshold of ⩾1 indicating. The economic viability value of one ton of tailings for three high-value TEs (Cs, Ta, Ga) ranged from $480.58 to $665.65. A PRPI ⩾1 serves as an industrial threshold for phyto-remining viability. TEs significantly influenced microbial community composition. Bacterial genera including Frankia, Clostridium, Methylocella, Methylocystis, Rhodopseudomonas, Sphingomonas, Burkholderia , and Geobacter showed positive exhibited negative correlations with most TEs. Fungal genera Ladophialophora, Talaromyces , and Piloderma showed negative correlations with all TEs. These findings clarify secondary recycling potential of tailings TEs, uncovers the linkage between TEs geochemistry and microbial assemblages, and support ecological remediation and resource recycling of abandoned mine tailings in agricultural areas.

Cd pollution-safe cultivar (Cd-PSC) is a feasible strategy to minimize Cd contamination in leafy vegetables. The shoot Cd concentrations of 23 Lactuca sativa cultivars under Cd stress ranged from 0.124 to 2.155 mg·kg^-1 with a maximum cultivar difference of 8 folds. Typical Cd-PSC C16 (L) and high-Cd-accumulating cultivar C13 (H) were screened to investigate the mechanisms of Cd accumulations in L. sativa through determining Cd concentrations, Cd subcellular distributions, phytochelatin profiles, and phytochelatin biosynthesis-related genes' expressions. Higher Cd distribution in a heat stable fraction in C13 (H) indicated that the high Cd accumulation trait of C13 (H) mainly depended on the Cd-phytochelatin complexes. Root phytochelatin concentrations were significantly elevated in C13 (H) (5.83 folds) than in C16 (L) (2.69 folds) (p < 0.05) under Cd stress. Significantly downregulated expressions of glutathione S-transferase rather than the regulation of phytochelatin synthesis genes in the root of C13 (H) might be responsible for sufficient glutathione supply for phytochelatins synthesis. These findings suggested that phytochelatin elevation in C13 (H) would favor the Cd root to shoot transportation, which provides new insights into the phytochelatin-related cultivar-dependent Cd accumulating characteristic in L. sativa.

Cadmium (Cd) contamination in edible agricultural products, especially in crops intended for consumption, has raised worldwide concerns regarding food safety. Breeding of Cd pollution-safe cultivars (Cd-PSCs) is an effective solution to preventing the entry of Cd into the food chain from contaminated agricultural soil. Molecular-assisted breeding methods, based on molecular mechanisms for cultivar-dependent Cd accumulation and bioinformatic tools, have been developed to accelerate and facilitate the breeding of Cd-PSCs. This review summarizes the recent progress in the research of the low Cd accumulation traits of Cd-PSCs in different crops. Furthermore, the application of molecular-assisted breeding methods, including transgenic approaches, genome editing, marker-assisted selection, whole genome-wide association analysis, and transcriptome, has been highlighted to outline the breeding of Cd-PSCs by identifying critical genes and molecular biomarkers. This review provides a comprehensive overview of the development of Cd-PSCs and the potential future for breeding Cd-PSC using modern molecular technologies.

Economic development level (EDL) cannot completely explain environmental behavior and participation (EBP) patterns as many other factors affect environmental performances, and the conflict of ‘Maslow’s Hierarchy Needs model’ or ‘Affluence hypothesis’ and ‘Challenge-response Model’ hypothesis has been continuously discussed. In the present study, a standardized two-dimensional array (STDA) model is employed to deliberate on the EDL-EBP relationship in different sub-groups with the highest ($21389.08) and the lowest ($5216.41) average capita GDPs in Guangdong Province, China. This is the first attempt to investigate the relationships between the regional EDL represented by capita GDP and public environmental behaviors represented by actual resident’s resource consumption, pollution emission and environmental participation in areas with similar natural and cultural condition, and an Environmental Effort Indicator (EEI) is established based on the STDA model. The results show that (1) the STDA model is applicable in distinguishing resident’s EBPs of 20 prefecture-level cities (PLCs) of Guangdong Province with rather different EDLs; (2) the relationship of EDL-EBP is not liner pattern and is behavior- and region-specific; (3) public participation plays an important role that is most decisive to the EEI; (4) the V-shaped EDL-EEI relationships can be explained each other with the EKC model. The formation of resident’s good environmental habits would be a long-term process and environmental education is a key way to accelerate the process and to maintain sustainable developments of the nature and human society.

Cadmium (Cd) contamination in edible agricultural products, especially in crops, has raised worldwide concerns regarding food safety consumption. This review summarizes the current knowledge of the applicable methods and perspectives for reducing Cd contamination of agricultural products. Agricultural approaches of soil amendments, irrigation management, microbial agent, and cropping patterns were systematically concluded to illustrate the developments and achievements in crop contamination management. The use of traditional soil amendments as well as novel nano-materials has contributed to producing safe crops in agricultural soil contaminated with Cd. This review provides an inspiring and promising tool for maintaining food safety by reducing Cd accumulation in edible agricultural products.

Proteomic analysis and biochemical tests were employed to investigate the critical biological processes responsible for the different cadmium (Cd) accumulations between two water spinach (Ipomoea aquatica) cultivars, QLQ and T308. QLQ, with lower shoot Cd accumulation and translocation factor than T308, possessed higher expression of cell wall biosynthesis and modification proteins in roots, together with higher lignin and pectin contents, higher pectin methylesterase activity, and lower pectin methylation. The results demonstrated that QLQ could more effectively restrict root-to-shoot Cd translocation by compartmentalizing more Cd in root cell walls. In contrast, T308 showed higher expression of the tricarboxylic acid (TCA) cycle, glutathione (GSH) metabolism, and heavy metal transporter proteins, accompanied by higher GSH content and glutathione S-transferase (GST) and glutathione reductase (GR) activity, which accelerated Cd uptake and translocation in T308. These findings revealed several critical biological processes responsible for cultivar-dependent Cd accumulation in water spinach, which are important for elucidating Cd accumulation and transport mechanisms in different cultivars.

To investigate the molecular mechanism of Cd-accumulating difference between Lactuca sativa cultivars, full-length transcriptome comparison, as well as biochemical validation, have been conducted between Cd pollution-safe cultivar (Cd-PSC, cv. LYDL) and high-Cd-accumulating cultivar (cv. HXDWQ). The full-length transcriptome of L. sativa cultivars was achieved for the first time. The results showed high Cd compartmentalization in the cell wall of cv. LYDL was ascribed to the enhanced cell wall biosynthesis under Cd stress, which was consistent with the high cellular debris Cd level (32.10–43.58%). The expression levels of transporter genes in cv. HXDWQ were about 1.19 to 1.21-fold higher than those in cv. LYDL, which was in accordance with the high ratio of easy migrative Cd chemical forms (68.59–81.98%), indicating the high Cd accumulation in the shoot of cv. HXDWQ was ascribed to the higher transportation capacity in cv. HXDWQ. Moreover, the Cd-induced endoplasmic reticulum (ER) stress was associated with the higher Cd detoxification and tolerance in cv. HXDWQ rather than in cv. LYDL. The study provides new insights into the Cd-induced transcriptomic difference between L. sativa cultivars and further contributes to the molecular breeding of L. sativa Cd-PSC.