Phytochelatin Synthesis Promotes Leaf Zn Accumulation of<i>Arabidopsis thaliana</i>Plants Grown in Soil with Adequate Zn Supply and is Essential for Survival on Zn-Contaminated Soil

Kühnlenz, Tanja; Hofmann, Christian; Uraguchi, Shimpei; Schmidt, Holger; Schempp, Stefanie; Weber, Michael; Lahner, Brett; Salt, David E.; Clemens, Stephan

doi:10.1093/pcp/pcw148

Cited by 51 publications

(49 citation statements)

References 49 publications

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“…Cysteine synthesis is widely recognized as a natural response by plants to toxic metal exposure. 68 Our findings suggests that the cysteine synthesis machinery was not completely disabled in these plants, perhaps due to differences in the type of soil used in the two studies.…”

Section: Distribution Of Zn In Brassica Juncea Root Biomassmentioning

confidence: 75%

Soil Bacteria Override Speciation Effects on Zinc Phytotoxicity in Zinc-Contaminated Soils

Adele

Ngwenya

Heal

et al. 2018

Environ. Sci. Technol.

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The effects of zinc (Zn) speciation on plant growth in Zn-contaminated soil in the presence of bacteria are unknown but are critical to our understanding of metal biodynamics in the rhizosphere where bacteria are abundant. A 6-week pot experiment investigated the effects of two plant growth promoting bacteria (PGPB), Rhizobium leguminosarum and Pseudomonas brassicacearum, on Zn accumulation and speciation in Brassica juncea grown in soil amended with 600 mg kg elemental Zn as three Zn species: soluble ZnSO and nanoparticles of ZnO and ZnS. Measures of plant growth were higher across all Zn treatments inoculated with PGPB compared to uninoculated controls, but Zn species effects were not significant. Transmission electron microscopy identified dense particles in the epidermis and intracellular spaces in roots, suggesting Zn uptake in both dissolved and particulate forms. X-ray absorption near-edge structure (XANES) analysis of roots revealed differences in Zn speciation between treatments. Uninoculated plants exposed to ZnSO contained Zn predominantly in the form of Zn phytate (35%) and Zn polygalacturonate (30%), whereas Zn cysteine (57%) and Zn polygalacturonate (37%) dominated in roots exposed to ZnO nanoparticles. Inoculation with PGPB increased (>50%) the proportion of Zn cysteine under all Zn treatments, suggesting Zn coordination with cysteine as the predominant mechanism of Zn toxicity reduction by PGPB. Using this approach, we show, for the first time, that although speciation is important, the presence of rhizospheric bacteria completely overrides speciation effects such that most of the Zn in plant tissue exists as complexes other than the original form.

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Section: Distribution Of Zn In Brassica Juncea Root Biomassmentioning

confidence: 75%

Soil Bacteria Override Speciation Effects on Zinc Phytotoxicity in Zinc-Contaminated Soils

Adele

Ngwenya

Heal

et al. 2018

Environ. Sci. Technol.

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“…There are reports regarding the effect of heavy metals on the upregulation of genes related to PCs biosynthesis (Mishra et al, 2006;Tennstedt et al, 2009). In safflower plants exposed to Zn excess, the induction of PC content can be due to induction of genes responsible for PC biosynthesis, like PC synthase (Mishra et al, 2006), and also it may partly be due to enhanced PC movement from roots through vascular tissues of the plant (Kühnlenz et al, 2016). There was no meaningful difference in the PC content between Zn-stressed and SA + Zn-treated plants.…”

Section: Discussionmentioning

confidence: 99%

Effects of exogenous salicylic acid and sodium nitroprusside on α-tocopherol and phytochelatin biosynthesis in zinc-stressed safflower plants

2018

Turk J Bot

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Introduction Zinc, the second most abundant transition metal after iron, is an essential element for normal growth and development at low concentrations. Zinc performs a substantial role as a cofactor for several enzymes and contributes to protein synthesis, as well as carbohydrate, nucleic acid, and lipid metabolism. However, elevated levels of Zn can cause the creation of excess reactive oxygen species (ROS), which influences plant growth and development (Kazemi et al., 2010; Li et al., 2013; Wang et al., 2013). Inductions in the levels of oxidative stress markers like malondialdehyde (MDA), H 2 O 2 , and the activity of lipoxygenase (LOX), an enzyme responsible for lipid peroxidation, have been reported under heavy metal stress (Gill and Tuteja, 2010). Plants have evolved several mechanisms to combat ROS-caused oxidative damage. These include antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR), and low-molecular-mass scavengers such as glutathione (GSH), α-tocopherol, and proline (Gill and Tuteja, 2010; Subba et al., 2014). Proline, a proteinogenic five-carbon α-amino acid, is among the foremost scavengers of ROS identified as indicators of several kind of environmental stress, like salinity and heavy metals (Li et al., 2013). It has also been reported that proline can act as a metal chelator (Liang et al., 2013). Metalloenzyme SOD operates as a first line of defense against ROS-induced injury, catalyzing the dismutation of highly reactive O 2 •to O 2 and H 2 O 2. The resulting H 2 O 2 is quickly averted by APX in the ascorbate-glutathione cycle or through other enzymes like GPX and CAT into cytoplasm and other cellular compartments (Gill and Tuteja, 2010). CAT, a heme-containing enzyme, is responsible for the dismutation of H 2 O 2 into H 2 O and O 2. GPX is able to decompose indole-3-acetic acid and is responsible for lignin production. This enzyme is involved in defense against various stresses by consuming H 2 O 2 (Gill and Tuteja, 2010).

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“…For example, PCs have been detected in the phloem of Brassica napus and implicated in Cd long-distance transport ( Mendoza-Cozatl et al 2008 ). Analyses of the AtPCS1-deficient A. thaliana mutant cad1-3 and another allele, cad1-6 , suggested PC-dependent Zn translocation from roots to shoots under adequate Zn condition ( Kühnlenz et al 2016 ). cad1-3 also shows reduced root-to-shoot Cd translocation ( Chen et al 2006 , Kühnlenz et al 2016 ), but exhibits increased As translocation from the root ( Liu et al 2010 ).…”

Section: Introductionmentioning

confidence: 99%

“…Analyses of the AtPCS1-deficient A. thaliana mutant cad1-3 and another allele, cad1-6 , suggested PC-dependent Zn translocation from roots to shoots under adequate Zn condition ( Kühnlenz et al 2016 ). cad1-3 also shows reduced root-to-shoot Cd translocation ( Chen et al 2006 , Kühnlenz et al 2016 ), but exhibits increased As translocation from the root ( Liu et al 2010 ). These findings in Arabidopsis suggest a potential of PCS to control Cd and/or As accumulation levels in seeds/grains.…”

Section: Introductionmentioning

confidence: 99%

Phytochelatin Synthase has Contrasting Effects on Cadmium and Arsenic Accumulation in Rice Grains

Uraguchi

Tanaka

Hofmann

et al. 2017

Plant and Cell Physiology

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Phytochelatin (PC) synthesis has been well demonstrated as a major metal tolerance mechanism in Arabidopsis thaliana, whereas its contribution to long-distance element transport especially in monocots remains elusive. Using rice as a cereal model, we examined physiological roles of Oryza sativa phytochelatin synthase 1 (OsPCS1) in the distribution and detoxification of arsenic (As) and cadmium (Cd), two toxic elements associated with major food safety concerns. First, we isolated four different transcript variants of OsPCS1 as well as one from OsPCS2. Quantitative real-time reverse transcription–PCR (RT-PCR) of each OsPCS transcript in rice seedlings suggested that expression of OsPCS1full, the longest OsPCS1 variant, was most abundant, followed by OsPCS2. Heterologous expression of OsPCS variants in PCS-deficient mutants of Schizosaccharomyces pombe and A. thaliana suggested that OsPCS1full possessed PCS activity in response to As(III) and Cd while the activity of other PCS variants was very low. To address physiological functions in toxic element tolerance and accumulation, two independent OsPCS1 mutant rice lines (a T-DNA and a Tos17 insertion line) were identified. The OsPCS1 mutants exhibited increased sensitivity to As(III) and Cd in hydroponic experiments, showing the importance of OsPCS1-dependent PC synthesis for rice As(III) and Cd tolerance. Elemental analyses of rice plants grown in soil with environmentally relevant As and Cd concentrations showed increased As accumulation and decreased Cd accumulation in grains of the T-DNA line. The Tos17 mutant also exhibited the reduced Cd accumulation phenotype. These contrasting effects on As and Cd distribution to grains suggest the existence of at least partially distinct PC-dependent pathways for As and Cd.

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Phytochelatin Synthesis Promotes Leaf Zn Accumulation ofArabidopsis thalianaPlants Grown in Soil with Adequate Zn Supply and is Essential for Survival on Zn-Contaminated Soil

Cited by 51 publications

References 49 publications

Soil Bacteria Override Speciation Effects on Zinc Phytotoxicity in Zinc-Contaminated Soils

Soil Bacteria Override Speciation Effects on Zinc Phytotoxicity in Zinc-Contaminated Soils

Effects of exogenous salicylic acid and sodium nitroprusside on α-tocopherol and phytochelatin biosynthesis in zinc-stressed safflower plants

Phytochelatin Synthase has Contrasting Effects on Cadmium and Arsenic Accumulation in Rice Grains

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