Bamboo vinegar regulates the phytoremediation efficiency of Perilla frutescens (L.) Britt. by reducing membrane lipid damage and increasing cadmium retention.

The gap between serious soil heavy metals pollution and inefficient soil remediation threatens human health. This study proposed a method to improve the phytoremediation efficiency using bamboo vinegar (BV) solution and the potential mechanism was discussed. The results demonstrated that the application of BV increases the content of cadmium (Cd) in vacuole and cell wall hemicellulose 2 in leaves of Perilla frutescens. Simultaneously, it enhanced enzyme activities of superoxide dismutase and catalase in leaves. Therefore, this process alleviated the damage of Cd to functional tissues of Perilla frutescens, thus improving the tolerance of plants to Cd. Moreover, the BV application reduced the Cd content bound by root cell wall pectin fractions and insoluble phosphate, subsequently improving the ability of oxalic acids to carry Cd to the aerial parts. Consequently, the aerial parts obtained a larger amount of Cd enrichment. Overall, the Transfer Factor of Cd from roots to stems and enrichment of Cd in Perilla frutescens were maximally increased by 57.70 % and 54.03 % with the application of 50-fold and 300-fold diluted BV under 2 mg·L-1 Cd stress, respectively. The results can provide a theoretical basis for the promotion of phytoremediation of Cd-contaminated soil treatment technology.

Alleviative effects of C60 fullerene nanoparticles on arsenate transformation and toxicity to Danio rerio.

Widely-used C60 fullerene nanoparticles (C60) result in their release into the aquatic environment, which may affect the distribution and toxicity of pollutants such as arsenic (As), to aquatic organism. In this study, arsenate (As(V)) accumulation, speciation and subcellular distribution was determined in Danio rerio (zebrafish) intestine, head and muscle tissues in the presence of C60. Meanwhile we compared how single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene oxide (GO) and graphene (GN) nanoparticles alter the behaviors of As(V). Results showed that C60 significantly inhibited As accumulation and toxicity in D. rerio, due to a decrease in total As and monomethylarsonic acid (MMA) and As(V) species concentrations, a lower relative distribution in the metal-sensitive fraction (MSF). It was attributed that C60 may coat As(V) ion channels and consequently, affect the secretion of digestive enzymes in the gut, favoring As excretion and inhibiting As methylation. Similarly, MWCNTs reduced the species concentration of MMA and As(V) in the intestines, low GSH (glutathione) contents in the intestine. Due to the disparity of other carbon-based nanomaterial morphologies, SWCNTs, GO and GN exhibited the various effects on the toxicity of As(V). In addition, the possible pathway of arsenobetaine (AsB) biosynthesis included migration from the intestine to muscle in D. rerio, with the precursor of AsB likely to be 2-dimethylarsinylacetic acid (DMAA). The results of this study suggest that C60 is beneficial for controlling As(V) pollution and reducing the impact of As(V) biogeochemical cycles throughout the ecosystem.

Subcellular Localization of Thioredoxin/Thioredoxin Reductase System-A Missing Link in Endoplasmic Reticulum Redox Balance.

The lumen of the endoplasmic reticulum (ER) is usually considered an oxidative environment; however, oxidized thiol-disulfides and reduced pyridine nucleotides occur there parallelly, indicating that the ER lumen lacks components which connect the two systems. Here, we investigated the luminal presence of the thioredoxin (Trx)/thioredoxin reductase (TrxR) proteins, capable of linking the protein thiol and pyridine nucleotide pools in different compartments. It was shown that specific activity of TrxR in the ER is undetectable, whereas higher activities were measured in the cytoplasm and mitochondria. None of the Trx/TrxR isoforms were expressed in the ER by Western blot analysis. Co-localization studies of various isoforms of Trx and TrxR with ER marker Grp94 by immunofluorescent analysis further confirmed their absence from the lumen. The probability of luminal localization of each isoform was also predicted to be very low by several in silico analysis tools. ER-targeted transient transfection of HeLa cells with Trx1 and TrxR1 significantly decreased cell viability and induced apoptotic cell death. In conclusion, the absence of this electron transfer chain may explain the uncoupling of the redox systems in the ER lumen, allowing parallel presence of a reduced pyridine nucleotide and a probably oxidized protein pool necessary for cellular viability.

Uptake, subcellular distribution, and fate of tetracycline in two wetland plants supplemented with microbial agents: Effect and mechanism.

The use of wetland plants in the context of phytoremediation is effective in the removal of antibiotics from contaminated water. However, the effectiveness and efficiency of many of these plants in the removal of antibiotics remain undetermined. In this study, the effectiveness of two plants-Phragmites australis and Iris pseudacorus-in the removal of tetracycline (TC) in hydroponic systems was investigated. The uptake of TC at the roots of I. pseudacorus and P. australis occurred at concentrations of 588.78 and 106.70 µg/g, respectively, after 7-day exposure. The higher uptake of TC in the root of I. pseudacorus may be attributed to its higher secretion of root exudates, which facilitate conditions conducive to the reproduction of microorganisms. These rhizosphere-linked microorganisms then drove the TC uptake, which was higher than that in the roots of P. australis. By elucidating the mechanisms underlying these uptake-linked outcomes, we found that the uptake of TC for both plants was significantly suppressed by metabolic and aquaporin inhibition, suggesting uptake and transport of TC were active (energy-dependent) and passive (aquaporin-dominated) processes, respectively. The subcellular distribution patterns of I. pseudacorus and P. australis in the roots were different, as expressed by differences in organelles, cell wall concentration levels, and transport-related dynamics. Additionally, the microbe-driven enhancement of the remediation capacities of the plants was studied comprehensively via a combined microbial-phytoremediation hydroponic system. We confirmed that the microbial agents increased the secretion of root exudates, promoting the variation of TC chemical speciation and thus enhancing the active transport of TC. These results contribute toward the improved application of wetland plants in the context of antibiotic phytoremediation.

Uptake, accumulation, translocation and transformation of seneciphylline (Sp) and seneciphylline-N-oxide (SpNO) by Camellia sinensis L.

Pyrrolizidine alkaloids (PAs) and their N-oxide (PANOs), as emerging environmental pollutants and chemical hazards in food, have become the focus of global attention. PAs/PANOs enter crops from soil and reach edible parts, but knowledge about their uptake and transport behavior in crops is currently limited. In this study, we chose tea (Camellia sinensis L.) as a representative crop and Sp/SpNO as typical PAs/PANOs to analyze their root uptake and transport mechanism. Tea roots efficiently absorbed Sp/SpNO, utilizing both passive and active transmembrane pathways. Sp predominantly concentrated in roots and SpNO efficiently translocated to above-ground parts. The prevalence of SpNO in cell-soluble fractions facilitated its translocation from roots to stems and leaves. In soil experiment, tea plants exhibited weaker capabilities for the uptake and transport of Sp/SpNO compared to hydroponic conditions, likely due to the swift degradation of these compounds in the soil. Moreover, a noteworthy interconversion between Sp and SpNO in tea plants indicated a preference for reducing SpNO to Sp. These findings represent a significant stride in understanding the accumulation and movement mechanisms of Sp/SpNO in tea plants. The insights garnered from this study are pivotal for evaluating the associated risks of PAs/PANOs and formulating effective control strategies.

Modulating Intracellular Dynamics for Optimized Intracellular Release and Transcytosis Equilibrium.

Active transcytosis-mediated nanomedicine transport presents considerable potential in overcoming diverse delivery barriers, thereby facilitating tumor accumulation and penetration. Nevertheless, the persistent challenge lies in achieving a nuanced equilibrium between intracellular interception for drug release and transcytosis for tumor penetration. In this study, a comprehensive exploration is conducted involving a series of polyglutamine-paclitaxel conjugates featuring distinct hydrophilic/hydrophobic ratios (HHR) and tertiary amine-oxide proportions (TP) (OPGA-PTX). The screening process, meticulously focused on delineating their subcellular distribution, transcytosis capability, and tumor penetration, unveils a particularly promising candidate denoted as OPPX, characterized by an HHR of 10:1 and a TP of 100%. OPPX, distinguished by its rapid cellular internalization through multiple endocytic pathways, selectively engages in trafficking to the Golgi apparatus for transcytosis to facilitate accumulation within and penetration throughout tumor tissues and simultaneously sorted to lysosomes for cathepsin B-activated drug release. This study not only identifies OPPX as an exemplary nanomedicine but also underscores the feasibility of modulating subcellular distribution to optimize the active transport capabilities and intracellular release mechanisms of nanomedicines, providing an alternative approach to designing efficient anticancer nanomedicines.

Accumulation, translocation, metabolism and subcellular distribution of mandipropamid in cherry radish: A comparative study under hydroponic and soil-cultivated conditions.

The accumulation and transportation of pesticides in plants can provide valuable insights to assess potential risks and ensure food safety. The uptake and downward translocation of mandipropamid were examined in hydroponic and soil-cultivated cherry radishes. The uptake of mandipropamid in cherry radish was rapid (bioconcentration factors of 1.1-10.7), whereas the downward translocation was limited (translocation factors of 0.1-0.9). The subcellular distribution results indicated a predominant accumulation in solid fractions of cherry radish (proportions of 52.9-98.7%), potentially because of the hydrophobicity (log Kow of 3.2) of mandipropamid. Owing to the decrease in half-life (>10%), the cultivation of cherry radish enhanced the dissipation of mandipropamid in both nutrient solutions (without stereoselectivity) and soils (with stereoselectivity). In addition, eleven metabolites and three pathways are proposed. This study provides valuable insights for the varying extent of translocation and proper utilization and safety evaluation of mandipropamid in crops.

BnXTH1 regulates cadmium tolerance by modulating vacuolar compartmentalization and the cadmium binding capacity of cell walls in ramie (Boehmeria nivea).

Xyloglucan endotransglucosylase/hydrolases (XTH) are cell wall-modifying enzymes important in plant response to abiotic stress. However, the role of XTH in cadmium (Cd) tolerance in ramie remains largely unknown. Here, we identified and cloned BnXTH1, a member of the XTH family, in response to Cd stress in ramie. The BnXTH1 promoter (BnXTH1p) demonstrated that MeJA induces the response of BnXTH1p to Cd stress. Moreover, overexpressing BnXTH1 in Boehmeria nivea increased Cd tolerance by significantly increasing the Cd content in the cell wall and decreasing Cd inside ramie cells. Cadmium stress induced BnXTH1-expression and consequently increased xyloglucan endotransglucosylase (XET) activity, leading to high xyloglucan contents and increased hemicellulose contents in ramie. The elevated hemicellulose content increased Cd chelation onto the cell walls and reduced the level of intracellular Cd. Interestingly, overexpressing BnXTH1 significantly increased the content of Cd in vacuoles of ramie and vacuolar compartmentalization genes. Altogether, these results evidence that Cd stress induced MeJA accumulation in ramie, thus, activating BnXTH1 expression and increasing the content of xyloglucan to enhance the hemicellulose binding capacity and increase Cd chelation onto cell walls. BnXTH1 also enhances the vacuolar Cd compartmentalization and reduces the level of Cd entering the organelles and soluble solution.

Calcium signaling facilitates chilling- and GA- induced dormancy release in tree peony.

Calcium plays a crucial role in plant growth and development, yet little is known about its function in endodormancy regulation. Tree peony (Paeonia suffruticosa), characterized by compound buds and large flowers, is well-known for its ornamental and medicinal value. To break bud dormancy release is a prerequisite of flowering and forcing culture, particularly during the Spring Festival. In this study, the Ca2+ chelator EGTA and Ca2+ channel blocker LaCl3 were applied, resulting in a significant delay in budburst during both chilling- and gibberellin (GA)- induced dormancy release in a dosage-dependent manner. As expected, the retardation of bud break was recovered by the supplementation of 30 mM CaCl2, indicating a facilitating role of calcium in dormancy release. Accordingly, several calcium-sensor-encoding genes including Calmodulin (CaM) and Ca2+-dependent protein kinases (CDPKs) were significantly up-regulated by prolonged chilling and exogenous GAs. Ultrastructure observations revealed a decline in starch grains and the reopening of transport corridors following prolonged chilling. Calcium deposits were abundant in the cell walls and intercellular spaces at the early dormant stage but were enriched in the cytosol and nucleus before dormancy release. Additionally, several genes associated with dormancy release, including EBB1, EBB3, SVP, GA20ox, RGL1, BG6, and BG9, were differentially expressed after calcium blocking and recovery treatments, indicating that calcium might partially modulate dormancy release through GA and ABA pathways. Our findings provide novel insights into the mechanism of dormancy release and offer potential benefits for improving and perfecting forcing culture technology in tree peonies.

Unveiling the absorption, translocation, and metabolism of penthiopyrad in pakchoi under hydroponic and soil-cultivated conditions.

The efficient use of pesticides has long been a topic of public concern, necessitating a thorough understanding of their movement in plants. This study investigates the translocation and distribution of penthiopyrad in pakchoi plants cultivated both in hydroponic and soil-cultivated conditions. Results indicate that penthiopyrad predominantly accumulates in the roots, with concentrations of 11.3-53.9 mg/kg following root application, and in the leaves, with concentrations of 2.0-17.1 mg/kg following foliar application. The bioconcentration factor exceeded 1, with values ranging from 1.2 to 23.9 for root application and 6.4 to 164.0 for foliar application, indicating a significant role in the absorption and accumulation processes. The translocation factor data, which were <1, suggest limited the translocations within pakchoi plants. The limitation may be attributed to the hydrophobic properties of penthiopyrad (log Kow = 3.86), as evidenced by its predominant distribution in the subcellular solid fractions of pakchoi tissues, accounting for 93.1% to 99.5% of the total proportion. Six metabolites (753-A-OH, M12, 754-T-DO, M11, PCA, and PAM) were identified in this study as being formed during this process. These findings provide valuable insights into the absorption, translocation, and metabolism of penthiopyrad in pakchoi.

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MiRNAs are a class of small non-coding RNAs, which regulate gene expression post-transcriptionally by partial complementary base pairing. Aberrant miRNA expressions have been reported in tumor tissues and peripheral blood of cancer patients. In recent years, artificial intelligence algorithms such as machine learning and deep learning have been widely used in bioinformatic research. Compared to traditional bioinformatic tools, miRNA target prediction tools based on artificial intelligence algorithms have higher accuracy, and can successfully predict subcellular localization and redistribution of miRNAs to deepen our understanding. Additionally, the construction of clinical models based on artificial intelligence algorithms could significantly improve the mining efficiency of miRNA used as biomarkers. In this article, we summarize recent development of bioinformatic miRNA tools based on artificial intelligence algorithms, focusing on the potential of machine learning and deep learning in cancer-related miRNA research.

Effects of uptake pathways on the accumulation, translocation, and metabolism of OPEs in rice: An emphasis on foliar uptake.

The often-overlooked importance of foliar absorption on the plant uptake of organic pollutants was investigated by an exposure chamber test. Rice seedlings were exposed to organophosphate esters (OPEs) through 8 scenarios arranged from 3 major uptake pathways: root uptake via solution, foliar uptake via gas, and foliar uptake via particles, to identify the contributions of these 3 uptake pathways and their influences on the translocation and metabolism of OPEs in rice. The concentration of OPEs in rice tissues showed an "additive effect" with the increase of exposure pathways. OPEs in rice shoots mainly originated from foliar uptake through particle (29.6 %-63.5 %) and gaseous (28.5 %-49.4 %) absorptions rather than root uptake (7.86 %-24.2 %) under the exposure condition. In comparison with stomal absorption, wax layer penetration was the main pathway for most OPEs to enter into leaves, especially for those compounds with high octanol-air partition coefficients. Although the subcellular distributions of OPEs in the rice tissues of the foliar exposure were slightly different from those of the root exposure, hydrophobic OPEs were mainly stored in the cell wall with hydrophilic OPEs mainly in the cytosol. The translocation of OPEs from the exposed tissue to the unexposed tissue were significantly negatively correlated with their octanol-water partition coefficients, but their basipetal translocation were limited. The result suggested that the translocation of OPEs within rice is prioritized over their degradation. This study deepens our understanding of the processes behind OPE uptake by rice and highlights the importance of foliar uptake, especially for those via particle absorption.

Cadmium induced changes in rhizosphere microecology to enhance Cd intake by Ligusticum sinense cv. Chuanxiong.

As the most famous and widely used traditional Chinese medicine (TCM), Ligusticum sinense cv. Chuanxiong (L. Chuaniong) has been affected by cadmium (Cd) exceeding with high ability of Cd accumulation. There is relatively little research on Cd absorption and storage process in L. Chuanxiong, which is an important reason for the poor remediation efficiency. Hence, this study takes L. Chuanxiong as the point of penetration to explore how L. Chuanxiong affects rhizobacteria through root exudates to alter soil Cd intake, as well as to explore the migration and storage of Cd in its body with 0.10 (T0), 5.00 (T5), 10.00 (T10) mg/kg Cd contaminations. The results showed that the relative abundance of amino acids and phospholipids secreted from L. Chuanxiong root noticeably increased with increasing Cd levels, which directly activated soil Cd or extremely significantly (P < 0.01) recruited bacteria such as Bacillus, Arthrobacter to indirectly increase Cd availability. Under the interaction of root exudates and rhizobacteria, Cd bioavailability increased by 80.00% in rhizosphere soil and Cd accumulation in L. Chuanxiong increased 5.44-6.65 mg/kg. Cd subcellular distribution analysis demonstrated that Cd was mainly stored in the root (10-fold more than in the leaf), whose Cd content was cytoderm>cytoplasm>organelle in tissues. The sequential extraction results found that non-soluble phosphate and protein-chelated Cd dominated (85.00-90.00%) in the cell, while Cd cheated with alcohol soluble protein, amino acid salts, water-soluble organic acid in cell was minimal (5.50%). The phenomenon indicated that L. Chuanxiong fixed Cd in root (the medical part) with low translocation ability. This study can provide theoretical support for the high-quality production of L. Chuanxiong and other root medical plant in heavy metal influenced sites.

Uptake mechanism, translocation, and transformation of organophosphate esters in water hyacinth (Eichhornia crassipes): A hydroponic study.

Owing to their dominant wastewater origin, bioavailability, and toxicity, the occurrence and behavior of organophosphate esters (OPEs) in aquatic systems have attracted considerable attention over the past two decades. Aquatic plants can accumulate and metabolize OPEs in water, thereby playing an important role in their behavior and fate in waterbodies. However, their uptake, translocation and transformation mechanisms in plants remain incompletely characterized. We investigated the accumulation and transformation of OPEs in water hyacinth (Eichhornia crassipes) through a series of hydroponic experiments using three representative OPEs, tris(2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), and triphenyl phosphate (TPP). These OPEs can not only be adsorbed onto and enter plant roots via passive diffusion pathways, which are facilitated by anion channels and/or aquaporins, but also can return to the solution when concentration gradients exist. After entry, hydrophilic TCEP showed a dominant distribution in the cell sap, strong acropetal transportability, and rapid translocation rate, whereas hydrophobic TPP was mostly retained in the root cell wall and therefore demonstrated weak acropetal transportability; TBEP with moderate hydrophilicity remained in the middle. All these OPEs can be transformed into diesters, which presented higher proportions in the cell sap and therefore have stronger acropetal transferability than their parent OPEs. TCEP exhibits the lowest biodegradability, followed by TPP and TBEP. These OPEs exerted apparent effects on plant growth, photosynthesis, and the diversity and composition of the rhizosphere microbial community.

Comparative study of the steady-state subcellular distribution of lysosome-associated membrane glycoprotein-2 (LAMP-2) isoforms with GYXXΦ-type tyrosine-based motifs that interact differently with four adaptor protein (AP) complexes.

Lysosome-associated membrane protein-1 and -2 (LAMP-1 and LAMP-2, respectively) are type I transmembrane proteins. LAMP-2 comprises three splice isoforms (LAMP-2A, -B and-C) with different cytoplasmic tails (CTs). These three CTs possess different tyrosine-based motifs (GYXXΦ, where Φ is a bulky hydrophobic amino acid) at their C-termini. Interactions between tyrosine-based motifs and µ-subunits of four tetrameric adaptor protein (AP) complexes are necessary for their vesicular transport to lysosomes. Little is known about how the interaction strengths of these tyrosine motifs with µ-subunits affect the localization of isoforms to lysosomes. The interactions were first investigated using a yeast two-hybrid system to address this question. LAMP-2A-CT interacted with all four µ-subunits (µ1, µ2, µ3A and µ4 of AP-1, AP-2, AP-3 and AP-4, respectively). The interaction with µ3A was more robust than that with other µ-subunits. LAMP-2B-CT interacted exclusively and moderately with µ3A. LAMP-2C-CT did not detectably interact with any of the four µ-subunits. Immunofluorescence microscopy showed that all isoforms were localized in late endosomes and lysosomes. LAMP-2C was present in the plasma membrane and early endosomes; however, LAMP-2A and -2B were barely detectable in these organelles. In cell fractionation, LAMP-2A was the most abundant in the dense lysosomes, whereas LAMP-2C was significantly present in the low-density fraction containing the plasma membrane and early endosomes, in addition to the dense lysosomes. LAMP-2B considerably existed in the low-density late endosomal fraction. These data strongly suggest that the LAMP-2 isoforms are distributed differently in endocytic organelles depending on their interaction strengths with AP-3.

Safe utilization evaluation of two typical traditional Chinese medicinal materials in Cd-contaminated soil based on the analysis of Cd transfer and AHP model.

Due to the increasing scarcity of wild resources, most traditional Chinese medicinal materials (TCMMs) in the market are produced via artificial cultivation. The widespread pollution of cadmium (Cd) in soil limits the safe cultivation and use of TCMMs. This study investigated Cd accumulation, distribution, and the medicinal component content under simulated field conditions to clarify the differences in the Cd absorption, transfer and detoxification mechanisms of Polygonatum cyrtonema Hua and Bletilla striata, and provide the preliminary safe utilization conditions of TCMMs based on the analytic hierarchy process (AHP). The results showed that the Cd content of P. cyrtonema Hua was lower than the safety threshold under a high soil Cd concentration of 0.91 mg/kg (Cd-L), while B. striata was safe only at a low Cd concentration of 0.25 mg/kg (CK). Cd at 0.91 mg/kg induced hormesis affecting the net increase in biomass and medicinal component content for both TCMMs, while P. cyrtonema Hua showed better potential for safe utilization. Additionally, P. cyrtonema Hua had stronger resistance to Cd stress, exhibiting superior characteristics for synergistic absorption of Cd with mineral elements, transfer to nonmedical part and safer fixation forms in subcellular components. In contrast, B. striata showed insufficient Cd tolerance, and Cd was easily accumulated in organelles to inhibit plant growth. Our findings may attract more attention to the safe cultivation of TCMMs and provide insight into guidance for the safe utilization of slightly Cd-contaminated soil.

Phytochelatin-Mediated Cultivar-Dependent Cd Accumulations of Lactuca sativa and Implication for Cd Pollution-Safe Cultivars Screening.

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.

Interactive effect of 24-epibrassinolide and silicon on the alleviation of cadmium toxicity in rice (Oryza sativa L.) plants.

Cadmium (Cd) pollution is a serious threat to food safety and human health. Minimization of Cd uptake and enhancing Cd tolerance in plants are vital to improve crop yield and reduce hazardous effects to humans. In this study, we investigate the effect of a synergistic system with phytohormone (24-Epibrassinolide, EBL) and silicon (Si) on Cd toxicity and accumulation of rice plants. The results revealed that Si, EBL and their combination rescued Cd-induced growth inhibition, as evidenced by the increased dry weight of root and shoot. The chlorophyll content and photosynthetic performance were improved. The activity of antioxidant enzymes (SOD, POD and CAT) was increased and oxidative stress was alleviated. More importantly, Cd content in root was decreased by 20.25%, 17.72% and 27.84%, while Cd content in shoot decreased by 21.17%, 16.47% and 25.88%, respectively. Moreover, Si, EBL and Si + EBL treatment enriched cell wall-bound Cd and reduced Cd toxicity to functional organelles. Meanwhile, the residual form of Cd was enriched and the highly toxic forms of Cd (inorganic and water-soluble Cd) were decreased. The joint application showed better effects than applying Si and EBL alone. Collectively, this study provides an effective way for Cd toxicity mitigation in rice plants.

Regulation of magnesium and calcium homeostasis in citrus seedlings under varying magnesium supply.

Magnesium (Mg) and calcium (Ca) are two essential macronutrients in plants; however, the characteristics of Mg and Ca concentrations in organ, subcellular and chemical forms and their relationships in citrus plants, especially under varying Mg supply, are not well understood. In this study, Citrus sinensis seedlings (cv. Xuegan) were cultivated in conditions of Mg deficiency (0 mmol Mg2+ L-1) and Mg sufficiency (2 mmol Mg2+ L-1) to investigate the responses of Mg and Ca homeostasis in different organs and fractions. Compared with Mg sufficiency, Mg deficiency significantly decreased root and shoot growth, with the shoot biomass reduction of branch organs was greater than that of parent organs. In addition to increasing the Ca concentration in the parent stem and lateral root organs, Mg deficiency significantly decreased the concentrations and accumulations of Mg and Ca in citrus seedlings, further altering their distribution in different organs. More than 50% of Ca and Mg were sequestrated in the cell wall and soluble fractions, respectively, with Mg concentration decreasing by 15.4% in roots and 46.9% in leaves under Mg deficiency, while Ca concentration decreased by 27.6% in roots and increased by 23.6% in parent leaves. Approximately 90% of Mg exists in inorganic, water-soluble, and pectate and protein-bound forms, and nearly 90% of Ca exists in water-soluble, pectate and protein-bound, phosphate and oxalate acid forms. Except for the decreased inorganic Mg in roots and water-soluble Mg and Ca in leaves, Mg deficiency increased the proportions of Mg and Ca in all chemical forms. However, Mg deficiency generally increased the Ca/Mg ratio in various organs, subcellular and chemical forms, with negative relationships between Mg concentration and Ca/Mg ratio, and the variations of Mg and Ca were highly separated between Mg supply and organs. In conclusion, our results provide insights into the effects of Mg supply on Mg and Ca homeostasis in citrus plants.

Uptake, Translocation, and Subcellular Distribution of Strobilurin Fungicides in Cucumber (Cucumis sativa L.).

The absorption, transport, and subcellular distribution of strobilurin fungicides (azoxystrobin, pyraclostrobin, and trifloxystrobin) have been studied in cucumbers. Under hydroponic laboratory conditions, pyraclostrobin and trifloxystrobin mainly accumulated in cucumber roots whereas azoxystrobin accumulated in cucumber leaves. In the subcellular distribution experiment, azoxystrobin mainly accumulated as a soluble component. Pyraclostrobin and trifloxystrobin accumulated more in the organelles and cell walls. Azoxystrobin and pyraclostrobin enter the root primarily through the apoplast pathway, whereas trifloxystrobin enters the root through the symplastic pathway. Azoxystrobin can be transported in cucumber through anion and cation channels, whereas pyraclostrobin and trifloxystrobin can be transported only through anion channels. This study has great significance in evaluating environmental risks and food safety.