Dataset Information

Silicon-Mediated Alleviation of Aluminum Toxicity by Modulation of Al/Si Uptake and Antioxidant Performance in Ryegrass Plants.

ABSTRACT: Silicon (Si) has been well documented to alleviate aluminum (Al) toxicity in vascular plants. However, the mechanisms underlying these responses remain poorly understood. Here, we assessed the effect of Si on the modulation of Si/Al uptake and the antioxidant performance of ryegrass plants hydroponically cultivated with Al (0 and 0.2 mM) in combination with Si (0, 0.5, and 2.0 mM). Exposure to Al significantly increased Al concentration, mainly in the roots, with a consequent reduction in root growth. However, Si applied to the culture media steadily diminished the Al concentration in ryegrass, which was accompanied by an enhancement in root dry matter production. A reduced concentration of Si in plant tissues was also observed when plants were simultaneously supplied with Al and Si. Interestingly, Si transporter genes (Lsi1 and Lsi2) were down-regulated in roots after Si or Al was applied alone; however, both Lsi1 and Lsi2 were up-regulated as a consequence of Si application to Al-treated plants, denoting that there is an increase in Si requirement in order to cope with Al stress in ryegrass. Whereas Al addition triggered lipid peroxidation, Si contributed to an attenuation of Al-induced oxidative stress by increasing phenols concentration and modulating the activities of superoxide dismutase (SOD), catalase, peroxidase, and ascorbate peroxidase antioxidant enzymes. Differential changes in gene expression of SOD isoforms (Mn-SOD, Cu/Zn-SOD, and Fe-SOD) and the profile of peroxide (H2O2) generation were also induced by Si in Al-stressed plants. This, to the best of our knowledge, is the first study to present biochemical and molecular evidence supporting the effect of Si on the alleviation of Al toxicity in ryegrass plants.

SUBMITTER: Pontigo S

PROVIDER: S-EPMC5404182 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Silicon-Mediated Alleviation of Aluminum Toxicity by Modulation of Al/Si Uptake and Antioxidant Performance in Ryegrass Plants.

Pontigo Sofía S Godoy Karina K Jiménez Héctor H Gutiérrez-Moraga Ana A Mora María de la Luz ML Cartes Paula P

Frontiers in plant science 20170425

Silicon (Si) has been well documented to alleviate aluminum (Al) toxicity in vascular plants. However, the mechanisms underlying these responses remain poorly understood. Here, we assessed the effect of Si on the modulation of Si/Al uptake and the antioxidant performance of ryegrass plants hydroponically cultivated with Al (0 and 0.2 mM) in combination with Si (0, 0.5, and 2.0 mM). Exposure to Al significantly increased Al concentration, mainly in the roots, with a consequent reduction in root g ...[more]

PMID: 28487719

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Project description:Al-Mg-Si series aluminum alloy is a heat-treatment-strengthened alloy. Research on the impact resistance of Al-Mg-Si series aluminum alloy is of great significance to expand its application in engineering. Taking 6082-T6 aluminum alloy as the concrete research object, using the split Hopkinson pressure bar (SHPB) device, the dynamic mechanical response of the material under different temperatures and average strain rates was studied, and the service performance of the material under extreme conditions was determined. The absolute temperature rise was introduced to optimize the existing constitutive model. The results show that when the environment temperature is 298.15~473.15 K under high-speed impact, the internal thermal softening effect of the material is dominant in the competition with the work hardening, resulting in a decrease in the flow stress of the material. Through the analysis of the real stress-strain curve, it was found that the elastic modulus of the material was negatively correlated with the strain rate, negatively correlated with the temperature, and showed an obvious temperature-softening effect. Yield strength was negatively correlated with temperature and positively correlated with strain rate, which showed an obvious strain rate hardening effect. Based on SEM microscopic analysis, it was found that under given conditions, adiabatic shear bands appeared in some samples, and their internal structures demonstrated obvious change. It was judged that when high-speed impact occurs, cracks are induced at the shear bands, and the cracks will continue to develop along the adiabatic shear bands, resulting in many oblique cracks which will gradually become larger and eventually lead to material failure. Finally, based on the model, the strain rate and temperature softening terms were improved, and a rise in adiabatic temperature rise was introduced. The improved model can better describe the strain rate effect of the material and accurately describe its flow stress. It provides a theoretical basis for the engineering application of materials.

Project description:Phosphobacteria, secreting organic acids and phosphatases, usually favor plant performance in acidic soils by increasing phosphorus (P) availability and aluminum (Al) complexing. However, it is not well-known how P-deficiency and Al-toxicity affect the phosphobacteria physiology. Since P and Al problems often co-occur in acidic soils, we have therefore proposed the evaluation of the single and combined effects of P-deficiency and Al-toxicity on growth, organic acids secretion, malate dehydrogenase (mdh) gene expression, and phosphatase activity of five Al-tolerant phosphobacteria previously isolated from ryegrass. These phosphobacteria were identified as Klebsiella sp. RC3, Stenotrophomona sp. RC5, Klebsiella sp. RCJ4, Serratia sp. RCJ6, and Enterobacter sp. RJAL6. The strains were cultivated in mineral media modified to obtain (i) high P in absence of Al-toxicity, (ii) high P in presence of Al-toxicity, (iii) low P in absence of Al-toxicity, and (iv) low P in presence of Al-toxicity. High and low P were obtained by adding KH2PO4 at final concentration of 1.4 and 0.05 mM, respectively. To avoid Al precipitation, AlCl3 × 6H2O was previously complexed to citric acid (sole carbon source) in concentrations of 10 mM. The secreted organic acids were identified and quantified by HPLC, relative mdh gene expression was determined by qRT-PCR and phosphatase activity was colorimetrically determined using p-nitrophenyl phosphate as substrate. Our results revealed that although a higher secretion of all organic acids was achieved under P-deficiency, the patterns of organic acids secretion were variable and dependent on treatment and strain. The organic acid secretion is exacerbated when Al was added into media, particularly in the form of malic and citric acid. The mdh gene expression was significantly up-regulated by the strains RC3, RC5, and RCJ6 under P-deficiency and Al-toxicity. In general, Al-tolerant phosphobacteria under P deficiency increased both acid and alkaline phosphatase activity with respect to the control, which was deepened when Al was present. The knowledge of this bacterial behavior in vitro is important to understand and predict the behavior of phosphobacteria in vivo. This knowledge is essential to generate smart and efficient biofertilizers, based in Al-tolerant phosphobacteria which could be expansively used in acidic soils.

Dataset Information

Silicon-Mediated Alleviation of Aluminum Toxicity by Modulation of Al/Si Uptake and Antioxidant Performance in Ryegrass Plants.

Publications

Silicon-Mediated Alleviation of Aluminum Toxicity by Modulation of Al/Si Uptake and Antioxidant Performance in Ryegrass Plants.

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