Reduced nodulation in alfalfa induced by arsenic correlates with altered expression of early nodulins

Lafuente, Alejandro; Pajuelo, Eloísa; Caviedes, Miguel A.; Rodríguez‐Llorente, Ignacio D.

doi:10.1016/j.jplph.2009.09.014

Cited by 46 publications

(12 citation statements)

References 23 publications

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“…Rather, plant traits including root necrosis, root hair damage, and a shorter length of the root zone that was subject to infection were implicated (Pajuelo et al, 2008). Transcript analysis indicated that AsIII exposure interferes with the expression of genes involved in early nodule development (Lafuente et al, 2010). Together, these results suggest that As contamination of soil has the potential to strongly decrease N 2 fixation in ecosystems involving legume-rhizobium symbioses.…”

Section: Direct Metabolic Consequences Of Arsenicmentioning

confidence: 99%

Arsenic Toxicity: The Effects on Plant Metabolism

Finnegan¹,

Chen²

2012

Front. Physio.

659

329

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The two forms of inorganic arsenic, arsenate (AsV) and arsenite (AsIII), are easily taken up by the cells of the plant root. Once in the cell, AsV can be readily converted to AsIII, the more toxic of the two forms. AsV and AsIII both disrupt plant metabolism, but through distinct mechanisms. AsV is a chemical analog of phosphate that can disrupt at least some phosphate-dependent aspects of metabolism. AsV can be translocated across cellular membranes by phosphate transport proteins, leading to imbalances in phosphate supply. It can compete with phosphate during phosphorylation reactions, leading to the formation of AsV adducts that are often unstable and short-lived. As an example, the formation and rapid autohydrolysis of AsV-ADP sets in place a futile cycle that uncouples photophosphorylation and oxidative phosphorylation, decreasing the ability of cells to produce ATP and carry out normal metabolism. AsIII is a dithiol reactive compound that binds to and potentially inactivates enzymes containing closely spaced cysteine residues or dithiol co-factors. Arsenic exposure generally induces the production of reactive oxygen species that can lead to the production of antioxidant metabolites and numerous enzymes involved in antioxidant defense. Oxidative carbon metabolism, amino acid and protein relationships, and nitrogen and sulfur assimilation pathways are also impacted by As exposure. Readjustment of several metabolic pathways, such as glutathione production, has been shown to lead to increased arsenic tolerance in plants. Species- and cultivar-dependent variation in arsenic sensitivity and the remodeling of metabolite pools that occurs in response to As exposure gives hope that additional metabolic pathways associated with As tolerance will be identified.

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Section: Direct Metabolic Consequences Of Arsenicmentioning

confidence: 99%

Arsenic Toxicity: The Effects on Plant Metabolism

Finnegan¹,

Chen²

2012

Front. Physio.

659

329

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“…Medicago truncatula (Gaertn.) (cv Jemalong) seeds were sterilized and pregerminated as described previously (Lafuente et al, 2010). Seedlings (0.5-1 cm root) were transferred to 1.5% Buffered Nodulation Medium (BNM)-agar medium (Ehrhardt et al, 1992) with or without 25 lM sodium arsenite and inoculated with 100 ll of an overnight culture of E. medicae MA11 (c. 10 8 colony forming units ml À1 ).…”

Section: Plant Growth Conditionsmentioning

confidence: 99%

“…Genomic DNA removal and reverse transcription were performed using the QuantiTect Reverse Transcription Kit (Qiagen). qPCR was performed as described previously (Lafuente et al, 2010), using three constitutively expressed genes (Msc27 (Microcallus suspension gene-27), c-tubulin and the translation initiation factor 5A-2) for normalization (Gallardo et al, 2007;Lafuente et al, 2010).…”

Section: Real Time Qpcrmentioning

confidence: 99%

“…However, data on the genetic basis of this behaviour are scarce. Lafuente et al (2010) reported low expression levels of several nodulin genes and reduced nodulation in the presence of As. Nevertheless, a global transcriptomic analysis has never been performed in legumes, although many transcriptomic studies have been carried out in nonlegumes, such as Arabidopsis thaliana (Abercrombie et al, 2008), rice (Oryza sativa; Chakrabarty et al, 2009;Huang et al, 2012;Tripathi et al, 2012a) and Brassica juncea (Srivastava et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Unraveling the effect of arsenic on the model Medicago–Ensifer interaction: a transcriptomic meta‐analysis

et al. 2014

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SummaryThe genetic regulation underlying the effect of arsenic (As(III)) on the model symbiosis Medicago-Ensifer was investigated using a combination of physiological (split-roots), microscopy and genetic (microarrays, qRT-PCR and composite plants) tools.Nodulation was very sensitive to As(III) (median inhibitory dose (ID50) = 20 lM). The effect on root elongation and on nodulation was local (nonsystemic). A battery of stress (salt, drought, heat shock, metals, etc.)-related genes were induced. Glutathione played a pivotal role in tolerance/detoxification, together with secondary metabolites ((iso)flavonoids and phenylpropanoids). However, antioxidant enzymes were not activated.Concerning the symbiotic interaction, molecular evidence suggesting that rhizobia alleviate As stress is for the first time provided. Chalcone synthase (which is involved in the first step of the legume-rhizobia cross-talk) was strongly enhanced, suggesting that the plants are biased to establish symbiotic interactions under As(III) stress. In contrast, 13 subsequent nodulation genes (involved in nodulation factors (Nod factors) perception, infection, thread initiation and progression, and nodule morphogenesis) were repressed.Overexpression of the ethylene responsive factor ERN in composite plants reduced root stress and partially restored nodulation, whereas overexpression of the early nodulin ENOD12 enhanced nodulation both in the presence and, particularly, in the absence of As, without affecting root elongation. Several transcription factors were identified, which could be additional targets for genetic engineering aiming to improve nodulation and/or alleviate root stress induced by this toxic.

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“…[6] Legume nodulation is very sensitive to even low concentrations of pollutants. [7][8][9] In particular, concentrations as low as 0.2 μM Cu 2+ induced a 10% *Corresponding author. Email: irodri@us.es reduction in Vigna unguiculata nodulation, [7] whereas 25 μM arsenite produced a 75% decrease in the total number of nodules in Medicago sativa.…”

Section: Introductionmentioning

confidence: 99%

Improving legume nodulation and Cu rhizostabilization using a genetically modified rhizobia

Delgadillo

Lafuente

Doukkali

et al. 2014

Environmental Technology

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The rhizobia-legume interaction has been proposed as an interesting and appropriate tool for rhizostabilization of soils contaminated with heavy metals. One of the main requirements to use this symbiosis is the availability of tolerant and symbiotically effective rhizobia. The aim of this work was to improve the symbiotic properties of the arsenic-resistant wild-type strain Ensifer medicae MA11 in Cu-contaminated substrates. The copAB genes from a Cu-resistant Pseudomonas fluorescens strain were expressed in E. medicae MA11 under the control of the nifH promoter. The resulting strain E. medicae MA11-copAB was able to alleviate the toxic effect of Cu in Medicago truncatula. At 300 µM Cu, root and shoot dry matter production, nitrogen content, number of nodules and photosynthetic rate were significantly reduced in plants inoculated with the wild-type strain. However, these parameters were not altered in plants inoculated with the genetically modified strain. Moreover, nodules elicited by this strain were able to accumulate twofold the Cu measured in nodules formed by the wild-type strain. In addition, the engineered E. medicae strain increased Cu accumulation in roots and decreased the content in shoots. Thus, E. medicae MA11-copAB increased the capacity of M. truncatula to rhizostabilize Cu, decreasing the translocation factor and avoiding metal entry into the food chain. The plasmid containing the nifH promoter-copAB construct could be a useful biotool for Cu rhizostabilization using legumes, since it can be transferred to different rhizobia microsymbionts of authoctonous legumes growing in Cu-contaminated soils.

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Reduced nodulation in alfalfa induced by arsenic correlates with altered expression of early nodulins

Cited by 46 publications

References 23 publications

Arsenic Toxicity: The Effects on Plant Metabolism

Arsenic Toxicity: The Effects on Plant Metabolism

Unraveling the effect of arsenic on the model Medicago–Ensifer interaction: a transcriptomic meta‐analysis

Improving legume nodulation and Cu rhizostabilization using a genetically modified rhizobia

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