Understanding straighthead: a complex physiological disorder of rice (Oryza sativa L.)

Chhabra, Rohit; Goyal, Priyanka; Singh, Tavisha; Vij, Lavanya

doi:10.1007/s11738-021-03309-y

Cited by 8 publications

(7 citation statements)

References 67 publications

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“…The accumulation of DMAs(V) has been shown to result in losses in rice yield due to the development of straighthead disease. 9,10 Therefore, understanding the transformation between iAs and methylated As compounds in paddy soil is crucial for food security and safety.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Accumulation of DMAs(V) in rice grain effectively reduces its toxicity to humans, , although it may have unintended consequences for rice plants. The accumulation of DMAs(V) has been shown to result in losses in rice yield due to the development of straighthead disease. , Therefore, understanding the transformation between iAs and methylated As compounds in paddy soil is crucial for food security and safety.…”

Section: Introductionmentioning

confidence: 99%

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Prevalence of Methylated Arsenic and Microbial Arsenic Methylation Genes in Paddy Soils of the Mekong Delta

Qiao

Liu

Palomo

et al. 2023

Environ. Sci. Technol.

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Microbially mediated inorganic-methylated arsenic (As) transformation in paddy soil is crucial to rice safety; however, the linkages between the microbial As methylation process and methylated As species remain elusive. Here, 62 paddy soils were collected from the Mekong River delta of Cambodia to profile As-related functional gene composition involved in the As cycle. The soil As concentration ranged from <1 to 16.6 mg kg–1, with average As contents of approximately 81% as methylated As and 54% as monomethylarsenate (MMAs(V)) in the phosphate- and oxalate-extractable fractions based on As sequential extraction analysis. Quantitative PCR revealed high arsenite-methylating gene (arsM) copy numbers, and metagenomics identified consistently high arsM gene abundance. The abundance of As-related genes was the highest in bacteria, followed by archaea and fungi. Pseudomonas, Bradyrhizobium, Burkholderia, and Anaeromyxobacter were identified as bacteria harboring the most genes related to As biotransformation. Moreover, arsM and arsI (As demethylation) gene-containing operons were identified in the metagenome-assembled genomes (MAGs), implying that arsM and arsI could be transcribed together. The prevalence of methylated As and arsM genes may have been overlooked in tropical paddy fields. The As methylation–demethylation cycle should be considered when manipulating the methylated As pool in paddy fields for rice safety.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prevalence of Methylated Arsenic and Microbial Arsenic Methylation Genes in Paddy Soils of the Mekong Delta

Qiao

Liu

Palomo

et al. 2023

Environ. Sci. Technol.

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“…9, 10 The accumulation of DMAs(V) has been shown to correlate with rice straight-head disease. 11, 12…”

Section: Introductionmentioning

confidence: 99%

“…9,10 The accumulation of DMAs(V) has been shown to correlate with rice straight-head disease. 11,12 Arsenic methylation is a microbially-mediated process involving the transformation of trivalent inorganic As (arsenite, As(III)) into mono-, di-, and trimethylated As compounds and is catalyzed by S-adenosyl-methionine methyltransferase (ArsM in prokaryotes). [13][14][15] Under flooded conditions, the paddy soil is anoxic, favoring the activity of anaerobic microbial As methylators, and, in turn, leading to greater accumulation of methylated As in rice grains as compared to dry cultivation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…However, there is evidence of a correlation between DMAs(V) accumulation in rice grains and rice straight-head disease, a condition that decreases crop yield. 11,12 Arsenic methylation is a microbially-mediated process involving the transformation of inorganic trivalent As (iAs(III)) into mono-, di-, and trimethylated As compounds and is catalyzed by S-adenosyl-methionine methyltransferase (ArsM in prokaryotes). [13][14][15] Generally, As methylation occurring under oxic conditions is proposed as an iAs(III)detoxifying process because although more toxic As compounds (monomethylarsonous acid (MMAs(III) and dimethylarsinous acid (DMAs(III)) are produced, they are rapidly oxidized in the presence of O 2 to their less toxic pentavalent counterparts (monomethylarsonic acid (MMAs(V) and dimethylarsinic acid (DMAs(V)).…”

Section: Introductionmentioning

confidence: 99%

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Growth substrate limitation enhances anaerobic arsenic methylation byParaclostridium bifermentansstrain EML

Qiao

Sallet

Meibom

et al. 2023

Preprint

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Microbial arsenic (As) methylation is established as a detoxification process under aerobic conditions (converting arsenite) to monomethylarsonic acid (MMAs(V))) but proposed to be a microbial warfare strategy under anoxic conditions due to the toxicity of its main product monomethylarsonous acid (MMAs(III)). Here, we leveraged a recently isolated anaerobic As methylator, Paraclostridium bifermentans strain EML to gain insights into this process. Strain EML was inoculated into a series of media that consisted of systematic dilutions of Reinforced Clostridial Broth (RCB) supplied with 25 μM arsenite to assess the impact of growth substrate availability on As methylation. Growth curves evidenced the sensitivity of strain EML to arsenite, and As speciation analysis revealed the production of MMAs(III). Concentrations of MMAs(III) were found to be positively corelated with the RCB medium dilution, suggesting that growth substrate availability plays an important role in the regulation of MMAs(III) production. Further, reverse-transcription quantitative PCR evidenced arsM gene transcription increased with RCB dilution. Thus, growth substrate limitation is interpreted to enhance arsM gene expression and the associated anaerobic As methylation. We propose that growth substrate competition between microorganisms may also lead to an increase in As methylation, providing support for a microbial warfare function for this process.

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Arsenic Dynamics in Paddy Rice Ecosystems and Human Exposure

Herath

Lin

Bundschuh

2022

Environmental Science and Engineering

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Understanding straighthead: a complex physiological disorder of rice (Oryza sativa L.)

Cited by 8 publications

References 67 publications

Prevalence of Methylated Arsenic and Microbial Arsenic Methylation Genes in Paddy Soils of the Mekong Delta

Prevalence of Methylated Arsenic and Microbial Arsenic Methylation Genes in Paddy Soils of the Mekong Delta

Growth substrate limitation enhances anaerobic arsenic methylation byParaclostridium bifermentansstrain EML

Arsenic Dynamics in Paddy Rice Ecosystems and Human Exposure

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