Effect of silicon spraying on rice photosynthesis and antioxidant defense system on cadmium accumulation.

Cadmium (Cd) pollution is a serious threat to food safety and human health. Minimizing Cd uptake and enhancing Cd tolerance in plants are vital to improve crop yield and reduce hazardous effects to humans. In this study, we designed three Cd concentration stress treatments (Cd1: 0.20 mg·kg-1, Cd2: 0.60 mg·kg-1, and Cd3: 1.60 mg·kg-1) and two foliar silicon (Si) treatments (CK: no spraying of any material, and Si: foliar Si spraying) to conduct pot experiments on soil Cd stress. The results showed that spraying Si on the leaves reduced the Cd content in brown rice by 4.79-42.14%. Si application increased net photosynthetic rate (Pn) by 1.77-4.08%, stomatal conductance (Gs) by 5.27-23.43%, transpiration rate (Tr) by 2.99-20.50% and intercellular carbon dioxide (CO2) concentration (Ci) by 6.55-8.84%. Foliar spraying of Si significantly increased the activities of superoxide dismutase (SOD) and peroxidase (POD) in rice leaves by 9.84-14.09% and 4.69-53.09%, respectively, and reduced the content of malondialdehyde (MDA) by 7.83-48.72%. In summary, foliar Si spraying protects the photosynthesis and antioxidant system of rice canopy leaves, and is an effective method to reduce the Cd content in brown rice.

Unveiling silicon-mediated cadmium tolerance mechanisms in mungbean (Vigna radiata (L.) Wilczek): Integrative insights from gene expression, antioxidant responses, and metabolomics.

Cadmium (Cd), one of the most phytotoxic heavy metals, is a major contributor to yield losses in several crops. Silicon (Si) is recognized for its vital role in mitigating Cd toxicity, however, the specific mechanisms governing this mitigation process are still not fully understood. In the present study, the effect of Si supplementation on mungbean (Vigna radiata (L.) Wilczek) plants grown under Cd stress was investigated to unveil the intricate pathways defining Si derived stress tolerance. Non-invasive leaf imaging technique revealed improved growth, biomass, and photosynthetic efficiency in Si supplemented mungbean plants under Cd stress. Further, physiological and biochemical analysis revealed Si mediated increase in activity of glutathione reductase (GR), ascorbate peroxidase (APX), and catalase (CAT) enzymes involved in reactive oxygen species (ROS) metabolism leading to mitigation of cellular damage and oxidative stress. Untargeted metabolomic analysis using liquid chromatography coupled with mass spectrometry (LC-MS/MS) provided insights into Si mediated changes in metabolites and their respective pathways under Cd stress. Alteration in five different metabolic pathways with major changes in flavanols and flavonoids biosynthesis pathway which is essential for controlling plants antioxidant defense system and oxidative stress management were observed. The information reported here about the effects of Si on photosynthetic efficiency, antioxidant responses, and metabolic changes will be helpful in understanding the Si-mediated resistance to Cd stress in plants.

Silicon induces ROS scavengers, hormone signalling, antifungal metabolites, and silicon deposition against brown stripe disease in sugarcane.

Bipolaris setariae is known to cause brown stripe disease in sugarcane, resulting in significant yield losses. Silicon (Si) has the potential to enhance plant growth and biotic resistance. In this study, the impact of Si on brown stripe disease was investigated across susceptible and resistant sugarcane varieties, utilizing four Si concentrations (0, 15, 30, and 45 g per barrel of Na2SiO3·5H2O). Si significantly reduced the incidence of brown stripe disease (7.41-59.23%) and alleviated damage to sugarcane growth parameters, photosynthetic parameters, and photosynthetic pigments. Submicroscopic observations revealed that Si induced the accumulation of silicified cells in leaves, reduced spore accumulation, decreased stomatal size, and protected organelles from B. setariae damage. In addition, Si increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), reduced reactive oxygen species production (malondialdehyde and hydrogen peroxide) and modulated the expression of genes associated with hormone signalling (PR1, TGA, AOS, AOC, LOX, PYL8, and SnRK2), leading to the accumulation of abscisic acid and jasmonic acid and inhibiting SA synthesis. Si also activated the activity of metabolism-related enzymes (polyphenol oxidase and phenylalanine ammonia lyase) and the gene expression of PAL-dependent genes (PAL, C4H, and 4CL), regulating the accumulation of metabolites, such as chlorogenic acid and lignin. The antifungal test showed that chlorogenic acid (15ug µL-1) had a significant inhibitory effect on the growth of B. setariae. This study is the first to demonstrate the inhibitory effect of Si on B. setariae in sugarcane, highlighting Si as a promising and environmentally friendly strategy for managing brown stripe disease.

Foliar spraying of Zn/Si affects Cd accumulation in paddy grains by regulating the remobilization and transport of Cd in vegetative organs.

The reduction of cadmium (Cd) accumulation in rice grains through biofortification of essential nutrients like zinc (Zn) and silicon (Si) is an area of study that has gained significant attention. However, there is limited understanding of the mechanism of Zn/Si interaction on Cd accumulation and remobilization in rice plants. This work used a pot experiment to examine the effects of Zn and Si applied singly or in combination on the physiological metabolism of Cd in different rice organs under Cd stress. The results revealed that: Zn/Si application led to a significant decrease in root Cd concentration and reduce the value of Tf Soil-Root in filling stage. The content of phytochelatin (PCs, particularly PC2) and glutathione (GSH) in roots, top and basal nodes were increased with Zn/Si treatment application. Furthermore, Zn/Si treatment promoted the distribution of Cd in cell wall during Cd stress. These findings suggest that Zn/Si application facilitates the compartmentalization of Cd within subcellular structures and enhances PCs production in vegetative organs, thereby reducing Cd remobilization. Zn/Si treatment upregulated the metabolism of amino acid components involved in osmotic regulation, secondary metabolite synthesis, and plant chelating peptide synthesis in vegetative organs. Additionally, it significantly decreased the accumulation of Cd in globulin, albumin, and glutelin, resulting in an average reduction of 50.87% in Cd concentration in milled rice. These results indicate that Zn/Si nutrition plays a crucial role in mitigating heavy metal stress and improving the nutritional quality of rice by regulating protein composition and coordinating amino acid metabolism balance.

Abiogenic silicon: Interaction with potentially toxic elements and its ecological significance in soil and plant systems.

Abiogenic silicon (Si), though deemed a quasi-nutrient, remains largely inaccessible to plants due to its prevalence within mineral ores. Nevertheless, the influence of Si extends across a spectrum of pivotal plant processes. Si emerges as a versatile boon for plants, conferring a plethora of advantages. Notably, it engenders substantial enhancements in biomass, yield, and overall plant developmental attributes. Beyond these effects, Si augments the activities of vital antioxidant enzymes, encompassing glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), among others. It achieves through the augmentation of reactive oxygen species (ROS) scavenging gene expression, thus curbing the injurious impact of free radicals. In addition to its effects on plants, Si profoundly ameliorates soil health indicators. Si tangibly enhances soil vitality by elevating soil pH and fostering microbial community proliferation. Furthermore, it exerts inhibitory control over ions that could inflict harm upon delicate plant cells. During interactions within the soil matrix, Si readily forms complexes with potentially toxic metals (PTEs), encapsulating them through Si-PTEs interactions, precipitative mechanisms, and integration within colloidal Si and mineral strata. The amalgamation of Si with other soil amendments, such as biochar, nanoparticles, zeolites, and composts, extends its capacity to thwart PTEs. This synergistic approach enhances soil organic matter content and bolsters overall soil quality parameters. The utilization of Si-based fertilizers and nanomaterials holds promise for further increasing food production and fortifying global food security. Besides, gaps in our scientific discourse persist concerning Si speciation and fractionation within soils, as well as its intricate interplay with PTEs. Nonetheless, future investigations must delve into the precise functions of abiogenic Si within the physiological and biochemical realms of both soil and plants, especially at the critical juncture of the soil-plant interface. This review seeks to comprehensively address the multifaceted roles of Si in plant and soil systems during interactions with PTEs.

Modulation of metal transporters, oxidative stress and cell abnormalities by synergistic application of silicon and titanium oxide nanoparticles: A strategy for cadmium tolerance in rice.

Heavy metals, especially cadmium (Cd), cause severe toxicity symptoms in crop plants. Applying nanoparticles (NPs) as nano-fertilizers is a novel approach to mitigating plants' Cd stress. However, knowledge about the combinational use of silicon (Si) and titanium dioxide (TiO2) NPs to mitigate Cd stress, especially in rice, must be highlighted. TiO2-NPs (15 mg L-1) and Si-NPs (2.5 mM) were applied alone and in combination to rice plants grown without (control; no Cd stress) and with (100 µM) Cd concentration. Results revealed that compared to the control plants, root length, shoot length, shoot fresh weight, and root dry weight of rice seedlings were significantly decreased by 25.43%, 26.64%, 34.13%, and 29.87% under Cd exposure. However, the synergistic effect of TiO2- and Si-NPs increased rice plants' shoot length, root length, root dry weight, and shoot fresh weight by 24.62%, 29.81%, 36.16%, and 33.07%, respectively, under the Cd-toxicity. The concentration of malondialdehyde (MDA) and H2O2 were amplified due to Cd stress, which leads to damage to the subcellular structures. Si and TiO2-NPs co-application improved the anti-oxidative enzymatic activities (catalase, peroxidase, superoxide dismutase) and an elevated concentration of non-enzymatic glutathione in Cd-exposed rice. The Cd accumulation was condensed by 21.37% and 19.7% in the shoot, while 48.31% and 45.65% in root tissues under Si-NPs + Cd and TiO2-NPs + Cd treatments compared to Cd-alone treated seedlings, respectively. The expression patterns of metal transporters, such as OsNramp1 and OsHMA3, were the highest when rice plants were cultivated under Cd stress and significantly reduced when treated with sole and combined Si- and TiO2-NPs treatments. In conclusion, combining Si- and TiO2-NPs significantly improved the antioxidant enzymatic activities, chlorophyll contents, biomass production, and reduced cellular damage. Despite limitations, our findings guide future research, addressing risks, optimizing concentrations, and assessing long-term effects that can balance agricultural progress with environmental sustainability.

Regulation of proline metabolism, AsA-GSH cycle, cadmium uptake and subcellular distribution in Brassica napus L. under the effect of nano-silicon.

Cadmium (Cd) is known to have detrimental effects on plant growth and human health. Recent studies showed that silicon nanoparticles (SNPs) can decrease Cd toxicity in plants. Therefore, a study was conducted using 50 µM Cd and 1.50 mM SNPs to investigate Cd uptake, subcellular distribution, proline (Pro) metabolism, and the antioxidant defense system in rapeseed seedlings. In this study, results indicated that Cd stress negatively affected rapeseed growth, and high Cd contents accumulated in both shoots and roots. However, SNPs significantly decreased Cd contents in shoots and roots. Moreover, substantial increases were found in root fresh weight by 40.6% and dry weight by 46.6%, as well as shoot fresh weight by 60.1% and dry weight by 113.7% with the addition of SNPs. Furthermore, the addition of SNPs alleviated oxidative injury by maintaining the ascorbate-glutathione (AsA-GSH) cycle and increased Pro biosynthesis which could be due to high activities of Δ1-pyrroline-5-carboxylate synthase (P5CS) and reductase (P5CR) and decreased proline dehydrogenase (ProDH) activity. Furthermore, the addition of SNPs accumulated Cd in the soluble fraction (42%) and cell wall (45%). Results indicate that SNPs effectively reduce Cd toxicity in rapeseed seedlings which may be effective in promoting both rapeseed productivity and human health preservation.

Silicon mediated redox homeostasis in the root-apex transition zone of rice plays a key role in aluminum tolerance.

The supply of silicon (Si) mitigates the aluminum (Al) toxicity on plant root growth, while the underlying mechanism remains unknown. Transition zone (TZ) emerges as the Al-toxicity target of plant root apex. The objective of the study was to evaluate the effect of Si on redox homeostasis in root-apex TZ of rice seedlings under Al stress. Si alleviated Al toxicity as revealed by promotion of root elongation and less Al accumulation. In Si-deprived plants, treatment with Al altered the normal distribution of superoxide anion (O2·-) and hydrogen peroxide (H2O2) in root tip. Al induced a significant increase of reactive oxygen species (ROS) in root-apex TZ, resulting in the peroxidation of membrane lipid and loss of plasma membrane integrity in root-apex TZ. However, Si greatly increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and enzymes involved in ascorbate-glutathione (AsA-GSH) cycle in root-apex TZ under Al stress, and enhanced AsA and GSH contents, which reduced ROS and callose contents, thereby reducing malondialdehyde (MDA) content and Evans blue uptake. These results allow to precise the changes of ROS in root-apex TZ after exposure to Al, and the positive role of Si in maintaining redox balance in root-apex TZ.

Silicon-mediated regulation of cadmium transport and activation of antioxidant defense system enhances Pennisetum glaucum resistance to cadmium stress.

Pennisetum glaucum is an important forage grass for livestock. However, the large accumulation of cadmium (Cd) in plant tissues increases the risk of heavy metals entering the food chain in Cd-contaminated soils. Silicon (Si) can inhibit cadmium (Cd) uptake and enhance tolerance of plant to Cd toxicity, but whether and how Si alleviates Cd toxicity in grass and the underlying mechanisms are unclear. The present study explored the differential mechanisms of silicon-induced Cd transport in apoplast and symplast, Cd distribution in root tissue and antioxidant defense system in P. glaucum under Cd stress through hydroponic and pot experiments. The present results showed that exogenous Si supply significantly reduced Cd concentrations in apoplast and symplast; Si treatment increased monosilicic acid concentration in apoplast and symplast of the roots and shoots under Cd stress. Elemental analysis of root microdomains showed that Si treatment increased the distribution of Cd and Si in the endodermis by 42.6% and 14.0%, respectively. Si alleviated the adverse influences of Cd on plant growth, which were manifested in root morphological traits and root activity. In addition, Si addition significantly increased the activities of catalase and superoxide dismutase by 37.0% and 72.7%, and improved the efficiency of the ascorbate-glutathione cycle in Cd-stress shoots. Furthermore, Si significantly reduced the contents of hydrogen peroxide and superoxide anion in Cd-stressed shoots by 16.6% and 48.7%, respectively. These findings demonstrate that Si enhances the resistance of P. glaucum to Cd stress through regulating Cd transport pathways and activating antioxidant defense systems.

Application of Exogenous Silicon for Alleviating Photosynthetic Inhibition in Tomato Seedlings under Low-Calcium Stress.

To address the low Ca-induced growth inhibition of tomato plants, the mitigation effect of exogenous Si on tomato seedlings under low-Ca stress was investigated using different application methods. We specifically analyzed the effects of root application or foliar spraying of 1 mM Si on growth conditions, leaf photosynthetic properties, stomatal status, chlorophyll content, chlorophyll fluorescence, ATP activity and content, Calvin cycle-related enzymatic activity, and gene expression in tomato seedlings under low vs. adequate calcium conditions. We found that the low-Ca environment significantly affected (reduced) these parameters, resulting in growth limitation. Surprisingly, the application of 1 mM Si significantly increased plant height, stem diameter, and biomass accumulation, protected photosynthetic pigments, improved gas exchange, promoted ATP production, enhanced the activity of Calvin cycle key enzymes and expression of related genes, and ensured efficient photosynthesis to occur in plants under low-Ca conditions. Interestingly, when the same amount of Si was applied, the beneficial effects of Si were more pronounced under low-Ca conditions that under adequate Ca. We speculate that Si might promote the absorption and transport of calcium in plants. The effects of Si also differed depending on the application method; foliar spraying was better in alleviating photosynthetic inhibition in plants under low-Ca stress, whereas root application of Si significantly promoted root growth and development. Enhancing the photosynthetic capacity by foliar Si application is an effective strategy for ameliorating the growth inhibition of plants under low-Ca stress.

Silicon inhibits gummosis in peach via ethylene and PpERF-PpPG1 pathway.

Silicon (Si) is abundant in nature, and it has been proved to be beneficial for the healthy growth and development of many plant species, improve plant stress resistance. Gummosis in peach is an invasive disease that causes widespread and serious damage. Mechanical damage and ethylene (ETH) can induce gummosis in peach shoots in the field. In this research, we found that Si as a chemical substance or signal to enhance plant resistance can reduce the synthesis of ETH, thereby inhibiting gummosis in peach. The results showed that Si can decrease the rate of gummosis, reduce the expression level of PpACS1 (1-aminocyclopropane -1-carboxylate synthase gene) and reduce the enzyme activity of polygalacturonase (PG). It was further discovered that Si can regulate the gene expression of PpERF21 and PpERF27. Yeast one-hybrid and dual-luciferase reporter assays showed that PpERF21 and PpERF27, through direct interaction with the promoter of PpPG1, inhibited the transcriptional activation of PpPG1. Overexpression of PpERF21 and PpERF27 effectively reduced fruit colloid production when bacterial cells harbouring the expression vector were used to instantaneously infect peach fruit. These results show that Si can inhibit the synthesis of ETH and mediate PpERF21 and PpERF27 expression to inhibit the expression of PpPG1, thereby inhibiting gummosis in peach.

Silicon-enhanced tolerance to cadmium toxicity in soybean by enhancing antioxidant defense capacity and changing cadmium distribution and transport.

Cadmium (Cd) is a widely distributed heavy metal that is toxic to plants and humans. Although silicon (Si) has been reported to reduce Cd accumulation and toxicity in plants, evidence on the functions of Si and its mechanisms in the possible alleviation of soybean are limited. Therefore, a controlled experiment was conducted to investigate the impacts and mechanisms of Si on Cd retention in soybean. Here, we determined the growth index, Cd distribution, and antioxidant activity systems of Si, as well as expression levels of differentially expressed genes (DEGs) in Si under Cd stress, and conducted RNA-seq analysis. We not only found that Si can significantly promote soybean plant growth, increase plant antioxidant activities, and reduce the Cd translocation factor, but also revealed that a total of 636 DEGs were shared between CK and Cd, CK and Cd + Si, and Cd and Cd + Si. Moreover, several genes were significantly enriched in antioxidant systems and Cd distribution and transport systems. Therefore, the expression status of Si-mediated Cd stress response genes is likely involved in improving oxidative stress and changing Cd uptake and transport, as well as improving plant growth that contributes to Si alleviating Cd toxicity in plants. Moreover, numerous potential target genes were identified for the engineering of Cd-tolerant cultivars in soybean breeding programs.

Deciphering the Molecular Mechanisms of Chilling Tolerance in Lsi1-Overexpressing Rice.

Improving tolerance to low-temperature stress during the rice seedling stage is of great significance in agricultural science. In this study, using the low silicon gene 1 (Lsi1)-overexpressing (Dular-OE) and wild-type rice (Dular-WT), we showed that Lsi1 overexpression enhances chilling tolerance in Dular-OE. The overexpression of the Lsi1 increases silicon absorption, but it was not the main reason for chilling tolerance in Dular-OE. Instead, our data suggest that the overexpression of a Lsi1-encoding NIP and its interaction with key proteins lead to chilling tolerance in Dular-OE. Additionally, we show that the high-mobility group protein (HMG1) binds to the promoter of Lsi1, positively regulating its expression. Moreover, Nod26-like major intrinsic protein (NIP)'s interaction with α and ß subunits of ATP synthase and the 14-3-3f protein was validated by co-immunoprecipitation (Co-IP), bimolecular fluorescent complementary (BiFC), and GST-pulldown assays. Western blotting revealed that the overexpression of NIP positively regulates the ATP-synthase subunits that subsequently upregulate calcineurin B-like interacting protein kinases (CIPK) negatively regulating 14-3-3f. Overall, these NIP-mediated changes trigger corresponding pathways in an orderly manner, enhancing chilling tolerance in Dular-OE.

Effect of FLOT2 Gene Expression on Invasion and Metastasis of Colorectal Cancer and Its Molecular Mechanism under Nanotechnology and RNA Interference.

The study is aimed at investigating the effect of the FLOT2 gene on invasion and metastasis of colorectal cancer (CRC) cells and the corresponding molecular mechanism by preparing polylysine-silicon nanoparticles. Specifically, polylysine was used to modify the silica nanoparticles prepared by the emulsification method to obtain polylysine-silicon nanoparticles. The characterization of polylysine-silicon nanoparticles was completed by nanoparticle size analyzer, laser particle size potentiometer, and transmission microscope. The influence of polylysine-silicon nanoparticles on the survival rate of CRC cell line HT-29 was detected using the method of 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). The FLOT2-siRNA expression vector was constructed and transfected with HT-29. The HT-29 transfected with empty plasmid was used as the negative control (NC). Western Blot (WB) and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect expression levels of FLOT2 gene and epithelial-mesenchymal transition- (EMT-) related genes. Transwell invasion assay, Transwell migration assay, and CCK8 assay were used to detect the cell invasion, migration, and proliferation. The results showed that the average particle size of polylysine-silicon nanoparticles was 30 nm, the potential was 19.65 mV, the particle size was 65.8 nm, and the dispersion coefficient was 0.103. At the same concentration, the toxicity of silicon nanoparticles to HT-29 was significantly lower than that of liposome reagent, and the transfection efficiency was 60%, higher than that of liposome reagent (40%). The mRNA level and protein expression of the FLOT2 gene in the FLOT2-siRNA group were significantly lower than those in the NC group (P < 0.01). The optical density (OD) value of the NC group and the blank control (CK) group were significantly higher than that of FLOT2-siRNA cells (P < 0.01). The OD value of FLOT2-siRNA cells was lower than that of NC cells at 48 h, 72 h, and 96 h (P < 0.01). The mRNA levels and protein expressions of MMP2 and vimentin in the FLOT2-siRNA group were significantly lower than those in the NC group and CK group (P < 0.01). The mRNA level and protein expression of the E-cadherin gene in the FLOT2-siRNA group were significantly higher than those in the NC group and CK group (P < 0.01). In conclusion, an RNA interference plasmid with high transfection efficiency and low cytotoxicity was established based on nanotechnology. siRNA-mediated FLOT2 protein inhibits the invasion, migration, and proliferation of CRC cells by regulating the expression changes of EMT-related genes, which provides a scientific basis for clinical treatment of CRC.

Characterization of silicon transporter gene family in Saccharum and functional analysis of the ShLsi6 gene in biotic stress.

Silicon, one of the most prevalent elements in the soil, is beneficial for plant growth and defense against different stresses. The silicon transporter gene (Lsi) plays an important role in the uptake and transport of silicon in higher plants. In this study, a total of 32 Lsi genes, including 20 SsLsi in sugarcane wild species Saccharum spontaneum, 5 ShLsi in Saccharum hybrid cultivar R570 and 7 SbLsi in sugarcane related species Sorghum bicolor, were identified and classified into three groups. Bioinformatics analysis showed that instability, hydrophobicity, localization of cell membranes and vacuoles were the main features of the Lsi proteins. Whole genome and segmental duplication contributed to the main expansion of Lsi gene family. Collinearity analysis of the Lsi genes showed that S. spontanum and R570 had a collinear relationship with monocotyledonous plants S. bicolor and Oryza sativa, but not with dicotyledonous plants Arabidopsis thaliana and Vitis vinifera. The replicated Lsi genes were mainly subjected to strong selection pressure for purification. The diverse cis-regulatory elements in the promoter of SsLsi, ShLsi and SbLsi genes suggested that they were widely involved in the response of plants to various stresses and the regulation of the growth and development. Transcriptome data and real time quantitative PCR analysis showed that the Lsi genes exhibited different expression profiles in sugarcane tissues and under Sporisorium scitamineum, drought and cold stresses. In addition, the cDNA and genomic DNA sequences of ShLsi6 that was homologous to SsLsi1b gene was cloned from Saccharum hybrid cultivar ROC22. Transient expression analysis showed that, compared with the control, Nicotiana benthamiana leaves which overexpressed the ShLsi6 gene showed a high sensitivity after inoculation with tobacco pathogens Ralstonia solanacearum and Fusarium solani var. coeruleum. This study provides important information for further functional analysis of Lsi genes and resistant breeding in sugarcane.

Perilymph metabolomic and proteomic MALDI-ToF profiling with porous silicon chips: A proof-of-concept study.

INTRODUCTION: Sensorineural hearing losses (SNHLs) are a significant public health issue, and the hearing loss field is desperately in need of effective therapy. Pathophysiological mechanisms are not yet clearly understood in the absence of validated methods to assess the inner ear content. Proteomic and metabolomic analysis of perilymph is opening new research perspectives for SNHLs. We aimed to demonstrate the feasibility of an innovative mass spectrometry (MS) strategy using porous silicon chips (PSCs) to investigate the low molecular weight (LMW) protein and metabolite content of human perilymph. Our second objective was to stratify perilymph samples according to their MS profiles and compare these results with clinical data. MATERIAL AND METHODS: Perilymph samples obtained during cochlear implant surgery from patients with SNHLs were retrieved from a validated biobank. To focus on LMW entities, we used a PSC enrichment protocol before MALDI-ToF MS analysis. PSCs were used as a LMW molecular preanalytical stabilizer and amplifier. Patients' clinical data and SNHL characteristics were retrieved retrospectively from medical charts. RESULTS: We successfully acquired and compared 59 exploitable MS profiles out of 71 perilymph samples. There was a good correlation between duplicates. Comparing both ears from the same patient, we found good reproducibility even when there was a one-year interval between samplings. We identified three distinct groups when comparing the samples' metabolomic profiles and four homogeneous groups comparing their LMW proteome profiles. Clinical data analysis suggested that some groups shared clinical or preanalytical characteristics. CONCLUSION: This proof-of-concept study confirms that LMW proteome and metabolome content of perilymph can be analyzed with PSCs. Based on protein profiles, we managed to stratify perilymp samples according to their molecular composition. These results must be confirmed with a larger population, and sampling methods require improvement, but this approach seems promising. In the future, this approach may pave the way for companion test strategies to precisely diagnose and define potential molecular targets for audioprotective therapies.

Silicon Reduces Aluminum-Induced Suberization by Inhibiting the Uptake and Transport of Aluminum in Rice Roots and Consequently Promotes Root Growth.

Silicon (Si) can alleviate aluminum (Al) toxicity in rice (Oryza sativa L.), but the mechanisms underlying this beneficial effect have not been elucidated, especially under long-term Al stress. Here, the effects of Al and Si on the suberization and development of rice roots were investigated. The results show that, as the Al exposure time increased, the roots accumulated more Al, and Al enhanced the deposition of suberin in roots, both of which ultimately inhibited root growth and nutrient absorption. However, Si restricted the apoplastic and symplastic pathways of Al in roots by inhibiting the uptake and transport of Al, thereby reducing the accumulation of Al in roots. Meanwhile, the Si-induced drop in Al concentration reduced the suberization of roots caused by Al through down-regulating the expression of genes related to suberin synthesis and then promoted the development of roots (such as longer and more adventitious roots and lateral roots). Moreover, Si also increased nutrient uptake by Al-stressed roots and thence promoted the growth of rice. Overall, these results indicate that Si reduced Al-induced suberization of roots by inhibiting the uptake and transport of Al in roots, thereby amending root growth and ultimately alleviating Al stress in rice. Our study further clarified the toxicity mechanism of Al in rice and the role of Si in reducing Al content and restoring root development under Al stress.

Silicon and mechanical damage increase polyphenols and vitexin in Passiflora incarnata L.

Passiflora incarnata L. is a species of global pharmacological importance, has not been fully studied in the context of cultivation and management. It is known that silicon acts on abiotic stress and promotes phenols synthesis. The practice of mechanical damage is widely used in P. incarnata crops, and its interaction with silicon can have a significant influence on plant metabolism. Therefore, our objective was to investigate the effects of silicon and mechanical damage on photosynthesis, polyphenols and vitexin of P. incarnata. The experiment was conducted in a factorial design with SiO2 concentrations (0, 1, 2, 3 mM) and presence or absence of mechanical damage. It was found that mechanical damage improved photosynthetic performance at lower concentrations or absence of silicon. Moreover, this condition promoted an increasing in vitexin concentration when SiO2 was not provided. The application of 3 mM Si is recommended to increase polyphenols and vitexin, without harming dry mass of aerial part. The interaction between silicon and mechanical damage could be a tool to increase agronomic yield and commercial value of the P. incarnata crop.

Combined application of zinc and silicon alleviates terminal drought stress in wheat by triggering morpho-physiological and antioxidants defense mechanisms.

Wheat is an important global staple food crop; however, its productivity is severely hampered by changing climate. Erratic rain patterns cause terminal drought stress, which affect reproductive development and crop yield. This study investigates the potential and zinc (Zn) and silicon (Si) to ameliorate terminal drought stress in wheat and associated mechanisms. Two different drought stress levels, i.e., control [80% water holding capacity (WHC) was maintained] and terminal drought stress (40% WHC maintained from BBCH growth stage 49 to 83) combined with five foliar-applied Zn-Si combinations (i.e., control, water spray, 4 mM Zn, 40 mM Si, 4 mM Zn + 40 mM Si applied 7 days after the initiation of drought stress). Results revealed that application of Zn and Si improved chlorophyll and relative water contents under well-watered conditions and terminal drought stress. Foliar application of Si and Zn had significant effect on antioxidant defense mechanism, proline and soluble protein, which showed that application of Si and Zn ameliorated the effects of terminal drought stress mainly by regulating antioxidant defense mechanism, and production of proline and soluble proteins. Combined application of Zn and Si resulted in the highest improvement in growth and antioxidant defense. The application of Zn and Si improved yield and related traits, both under well-watered conditions and terminal drought stress. The highest yield and related traits were recorded for combined application of Zn and Si. For grain and biological yield differences among sole and combined Zn-Si application were statistically non-significant (p>0.05). In conclusion, combined application of Zn-Si ameliorated the adverse effects of terminal drought stress by improving yield through regulating antioxidant mechanism and production of proline and soluble proteins. Results provide valuable insights for further cross talk between Zn-Si regulatory pathways to enhance grain biofortification.

Bioglass could increase cell membrane fluidity with ion products to develop its bioactivity.

OBJECTIVES: Silicate bioactive glass (BG) has been widely demonstrated to stimulate both of the hard and soft tissue regeneration, in which ion products released from BG play important roles. However, the mechanism by which ion products act on cells on cells is unclear. MATERIALS AND METHODS: Human umbilical vein endothelial cells and human bone marrow stromal cells were used in this study. Fluorescence recovery after photobleaching and generalized polarization was used to characterize changes in cell membrane fluidity. Migration, differentiation and apoptosis experiments were carried out. RNA and protein chip were detected. The signal cascade is simulated to evaluate the effect of increased cell membrane fluidity on signal transduction. RESULTS: We have demonstrated that ion products released from BG could effectively enhance cell membrane fluidity in a direct and physical way, and Si ions may play a major role. Bioactivities of BG ion products on cells, such as migration and differentiation, were regulated by membrane fluidity. Furthermore, we have proved that BG ion products could promote apoptosis of injured cells based on our conclusion that BG ion products increased membrane fluidity. CONCLUSIONS: This study proved that BG ion products could develop its bioactivity on cells by directly enhancing cell membrane fluidity and subsequently affected cell behaviours, which may provide an explanation for the general bioactivities of silicate material.