Lead (Pb) is among the most toxic heavy metals in biological systems and causes toxicity from seed germination to yield formation. High Pb concentrations lead to oxidative damage and impair water relation and nutrition uptake in plants. Rye (Secale cereale L.) is an abiotic stress-tolerant crop, distributed in Eastern and Central Europe. Pb concentration in soils higher than 30 mg kg-1 is commonly toxic to plants. This study investigated the effects of different Pb concentrations [0, 100, 200 and 400 mu M of Pb(NO3)2] on mineral element concentrations (B, Ca, Cu, Fe, K, Mg, Mn, Na and Zn) in rye plants. After 15 days of Pb stress, the levels of mineral elements (B, Ca, Cu, Fe, K, Mg, Zn, Mn and Na), and Pb accumulation were detected using by ICP-OES (Inductively coupled plasma-optical emission spectrometry) in leaves and roots. Under 0, 100, 200 and 400 mu M Pb application, the Pb accumulation varied between 0.005-2.94 and 5.63-13.63 mg kg-1 in leaves, and 0.03-69.34-168.11-329.74 mg kg-1 in roots, respectively. Roots accumulated higher levels of Pb than the leaves. The amounts of Na, Fe and B concentrations reduced, whereas the contents of Ca, K, Mn, Cu, and Zn increased in both leaves and roots in a concentration-dependent manner. The maximum rate of increase or decrease in elemental contents was recorded for 400 mu M Pb-exposed plants. In addition, Mg content increased in leaves, but decreased in roots. Overall, our findings suggest that Pb-exposure causes alterations in mineral element concentrations in a concentration-dependent manner, which could be useful to make risk assessments for Pb pollution in agricultural lands.

Industrial hemp is a crop with a high tolerance and accumulation of lead (Pb). Improving the Pb tolerance and accumulation capacity of industrial hemp is of great scientific and practical importance. This study utilized a pot with soil contaminated with Pb to investigate the differences in Pb tolerance between two industrial hemp varieties, Yunma1 (YM) and Shaanxi Industrial Hemp (SM), under Pb stress. The results indicated that Pb mainly accumulates in the roots of YM and SM (70-80%), with YM having a higher Pb accumulation than SM. It is worth nothing that under high Pb concentration conditions (5000 mg/kg), the Pb accumulation capacity of YM is twice that of SM. Accumulation characteristics of Pb in different plant tissues followed the pattern: roots > stems > leaves > fibers > seeds. In YM, approximately 70% of the absorbed Pb was fixed in the roots and 30% was transported to the above-ground parts. In contrast, SM transported more than 50% of absorbed Pb by roots to the above-ground areas, causing some degree of damage to stems and leaves. Even when Pb concentrations exceed 4000 mg/kg, YM exhibits strong tolerance (tolerance index greater than 90%), with normal growth and no signs of toxicity. However, SM showed a tolerance level of < 50% at high Pb concentrations, with significant heavy metal toxicity symptoms in the above-ground areas. These results provide important information for the remediation of Pb contaminated soils in mining areas.

Soil Pb contamination is inevitable, as a result of phosphate mining. It is essential to explore more effective Pb remediation approaches in phosphate mining wasteland soil to ensure their viability for a gradual return of soil quality for cultivation. In this study, a Pb-resistant urease-producing bacterium, Serratia marcescens W1Z1, was screened for remediation using microbially induced carbonate precipitation (MICP). Magnesium polypeptide (MP) was prepared from soybean meal residue, and the combined remediation of Pb contamination with MP and MICP in phosphate mining wasteland soil was studied. Remediation of Pb using a combination of MP with MICP strain W1Z1 (WM treatment) was the most effective, with the least exchangeable Pb at 30.37% and the most carbonate-bound Pb at 40.82%, compared to the other treatments, with a pH increase of 8.38. According to the community analysis, MP moderated the damage to microbial abundance and diversity caused by MICP. Total nitrogen (TN) was positively correlated with Firmicutes, pH, and carbonate-bound Pb. Serratia inoculated with strain W1Z1 were positively correlated with bacteria belonging to the Firmicutes phylum and negatively correlated with bacteria belonging to Proteobacteria. The available phosphate (AP) in the phosphate mining wasteland soil could encapsulate the precipitated Pb by ion exchange with carbonate, making it more stable. Combined MPMICP remediation of Pb contamination in phosphate mining wasteland soil was effective and improved the soil microenvironment.

Lead (Pb) is a highly toxic contaminant that is ubiquitously present in the ecosystem and poses severe environmental issues, including hazards to soil-plant systems. This review focuses on the uptake, accumulation, and translocation of Pb metallic ions and their toxicological effects on plant morpho-physiological and biochemical attributes. We highlight that the uptake of Pb metal is controlled by cation exchange capacity, pH, size of soil particles, root nature, and other physiochemical limitations. Pb toxicity obstructs seed germination, root/shoot length, plant growth, and final crop-yield. Pb disrupts the nutrient uptake through roots, alters plasma membrane permeability, and disturbs chloroplast ultrastructure that triggers changes in respiration as well as transpiration activities, creates the reactive oxygen species (ROS), and activates some enzymatic and non-enzymatic antioxidants. Pb also impairs photosynthesis, disrupts water balance and mineral nutrients, changes hormonal status, and alters membrane structure and permeability. This review provides consolidated information concentrating on the current studies associated with Pb-induced oxidative stress and toxic conditions in various plants, highlighting the roles of different antioxidants in plants mitigating Pb-stress. Additionally, we discussed detoxification and tolerance responses in plants by regulating different gene expressions, protein, and glutathione metabolisms to resist Pb-induced phytotoxicity. Overall, various approaches to tackle Pb toxicity have been addressed; the phytoremediation techniques and biochar amendments are economical and eco-friendly remedies for improving Pb-contaminated soils.