Arsenic accumulation in Pteris vittata: Time course, distribution, and arsenic-related gene expression in fronds and whole plantlets

Effectiveness of light-emitting diodes for arsenic and mercury accumulation by Ceratophyllum demersum L.: An innovative advancement in phytoremediation technology

Light Emitting Diodes (LEDs) have emerged as a tool with great potential in the field of phytoremediation, offering a novel approach to enhance the efficiency of plant-based remediation techniques. In this work investigated the influence of LEDs on the phytoremediation of arsenic (As) and mercury (Hg) by Ceratophyllum demersum L., propagated using tissue culture methods. In addition, the biochemical properties of the plants exposed to metal toxicity were examined. Phytoremediation experiments employed concentrations of As (0.01-1.0 mg/L) and Hg (0.002-0.2 mg/L), with application periods set at 1, 7, 14, and 21 days. In addition to white, red and blue LEDs, white fluorescent light was used for control purposes in the investigations. A positive correlation was observed between higher metal concentrations, extended exposure times, and increased metal accumulation in the plants. Red LED light yielded the highest level of heavy metal accumulation, while white fluorescent light resulted in the lowest accumulation level. Examination of the biochemical parameters of the plants, including photosynthetic pigment levels, protein quantities, and lipid peroxidation, revealed a pronouncedly enhanced performance in specimens subjected to red and blue LED illumination, surpassing outcomes observed in other light treatments. The findings of this study introduce innovative avenues for the effective utilization of red and blue LED lights in the realm of phytoremediation research. Thus, the interaction between LEDs, tissue culture, and the phytoremediation process could lead to synergistic effects that contribute to more effective and sustainable remediation strategies.

Transporters and phytohormones analysis reveals differential regulation of ryegrass (Lolium perenne L.) in response to cadmium and arsenic stresses

Cadmium (Cd) and arsenic (As) are two highly toxic heavy metals and metalloids that coexist in many situations posing severe threats to plants. Our investigation was conducted to explore the different regulatory mechanisms of ryegrass (Lolium perenne L.) responding to individual and combined Cd and As stresses in hydroponics. Results showed that the ryegrass well-growth phenotype was not affected by Cd stress of 10 mg·L-1. However, As of 10 mg·L-1 caused rapid water loss, proline surge, and chlorosis in shoots, suggesting that ryegrass was highly sensitive to As. Transcriptomic analysis revealed that the transcription factor LpIRO2 mediated the upregulation of ZIP1 and YSL6 that played an important role in Cd tolerance. We found that the presence of As caused the overexpression of LpSWT12, a process potentially regulated by bHLH14, to mitigate hyperosmolarity. Indoleacetic acid (IAA) and abscisic acid (ABA) contents and expression of their signaling-related genes were significantly affected by As stress rather than Cd. We predict a regulatory network to illustrate the interaction between transporters, transcription factors, and signaling transduction, and explain the antagonism of Cd and As toxicity. This present work provides a research basis for plant protection from Cd and As pollution.

As-hyperaccumulator Pteris vittata and non-hyperaccumulator Pteris ensiformis under low As-exposure: Transcriptome analysis and implication for As hyperaccumulation

Soil contamination by arsenic (As) poses potential health risks to humans. As-hyperaccumulator P. vittata has been used in As-contaminated soils for phytoremediation. Clarifying the mechanisms of its As-hyperaccumulation is critical to enhance its efficiency in phytoremediation. Here, based on transcriptome analysis, we determined the concentration-dependent patterns of As-related gene families by comparing As-hyperaccumulator P. vittata and non-hyperaccumulator P. ensiformis after exposing to 20 µM arsenate (AsV). As expected, arsenic induced more stress in P. ensiformis than P. vittata. Based on gene ontology, differences in transporter activity are probably responsible for their differential As accumulation. Though As exposure induced expression of phosphate transporter PvPht1;4 for AsV absorption in both plants, stronger AsV reduction, AsIII transport, and AsIII-GSH complexation were found in P. ensiformis roots. Unlike P. ensiformis, As metabolism processes occurred mainly in P. vittata fronds. Notably, tonoplast-localized ACR3s were only present in P. vittata, making it more effective in sequestrating AsIII into frond vacuoles. Further, vesicle As transformation via PvGAPC1 (glyceraldehyde 3-phosphate dehydrogenase), PvOCT4 (organic cation transporter 4), and PvGSTF1 (glutathione S-transferase) contributed little to As-hyperaccumulation. This study provides information on critical genes responsible for As-hyperaccumulation by P. vittata, which can be applied to construct As-hyperaccumulating plants by genetic engineering to enhance their phytoremediation efficiency in As-contaminated soils.

Intercropping efficiency of Pteris vittata with two legume plants: Impacts of soil arsenic concentrations

Intercropping of hyperaccumulators with crops has emerged as a promising method for remediating arsenic (As)-contaminated soil in agroecosystems. However, the response of intercropping hyperaccumulators with different types of legume plants to diverse gradients of As-contaminated soil remains poorly understood. In this study, we assessed the response of plant growth and accumulation of an As hyperaccumulator (Pteris vittata L.) intercropped with two legume plants to three gradients of As-contaminated soil. Results indicated that soil As concentration had a substantial effect on the As uptake by plants. P. vittata growing in slightly As-contaminated soil (80 mg kg^-1) exhibited higher As accumulation (1.52-5.49 folds) than those in higher As-contaminated soil (117 and 148 mg kg^-1), owing to the lower soil pH in high As-contaminated soil. Intercropping with Sesbania cannabina L. increased As accumulation in P. vittata by 19.3%- 53.9% but decreased in intercropping with Cassia tora L. This finding was attributed to S. cannabina providing more NO₃^--N to P. vittata to support its growth, and higher resistance to As. The decreased rhizosphere pH in the intercropping treatment also resulted in the increased As accumulation in P. vittata. Meanwhile, the As concentrations in the seeds of the two legume plants met the national food standards(<0.5 mg kg^-1). Therefore, the intercropping P. vittata with S. cannabina is a highly effective intercropping system in slightly As-contaminated soil and provides a potent method for As phytoremediation.