Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis

Ma del Carmen A. González-Chávez, Bradley Miller, Ignacio Eduardo Maldonado-Mendoza, Kirk Scheckel, Rogelio Carrillo-González

Research output: Contribution to journalArticleResearchpeer-review

17 Citations (Scopus)

Abstract

The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment invitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (μ-XRF), and microspectroscopic X-ray absorption near edge structure (μ-XANES), we observed that As(V) is absorbed after 1h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. μ-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3h after arsenic exposure and was completed after 6h. Principal component analysis (PCA) and linear combination fitting (LCF) of μ-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites. © 2014 The British Mycological Society.
Original languageAmerican English
Pages (from-to)444-452
Number of pages9
JournalFungal Biology
DOIs
StatePublished - 1 Jan 2014

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Synchrotrons
Glomus intraradices
Arsenic
arsenic
Radiation
Fungi
Hyphae
fungus
hyphae
mycorrhizal fungi
radiation
analysis
Iron
X-radiation
Hydroxides
X-Rays
iron hydroxides
Arsenicals
Daucus carota

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González-Chávez, Ma del Carmen A. ; Miller, Bradley ; Maldonado-Mendoza, Ignacio Eduardo ; Scheckel, Kirk ; Carrillo-González, Rogelio. / Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis. In: Fungal Biology. 2014 ; pp. 444-452.
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abstract = "The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment invitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (μ-XRF), and microspectroscopic X-ray absorption near edge structure (μ-XANES), we observed that As(V) is absorbed after 1h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. μ-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3h after arsenic exposure and was completed after 6h. Principal component analysis (PCA) and linear combination fitting (LCF) of μ-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites. {\circledC} 2014 The British Mycological Society.",
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Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis. / González-Chávez, Ma del Carmen A.; Miller, Bradley; Maldonado-Mendoza, Ignacio Eduardo; Scheckel, Kirk; Carrillo-González, Rogelio.

In: Fungal Biology, 01.01.2014, p. 444-452.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis

AU - González-Chávez, Ma del Carmen A.

AU - Miller, Bradley

AU - Maldonado-Mendoza, Ignacio Eduardo

AU - Scheckel, Kirk

AU - Carrillo-González, Rogelio

PY - 2014/1/1

Y1 - 2014/1/1

N2 - The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment invitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (μ-XRF), and microspectroscopic X-ray absorption near edge structure (μ-XANES), we observed that As(V) is absorbed after 1h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. μ-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3h after arsenic exposure and was completed after 6h. Principal component analysis (PCA) and linear combination fitting (LCF) of μ-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites. © 2014 The British Mycological Society.

AB - The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment invitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (μ-XRF), and microspectroscopic X-ray absorption near edge structure (μ-XANES), we observed that As(V) is absorbed after 1h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. μ-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3h after arsenic exposure and was completed after 6h. Principal component analysis (PCA) and linear combination fitting (LCF) of μ-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites. © 2014 The British Mycological Society.

U2 - 10.1016/j.funbio.2014.03.002

DO - 10.1016/j.funbio.2014.03.002

M3 - Article

SP - 444

EP - 452

JO - Fungal Biology

JF - Fungal Biology

SN - 1878-6146

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