Oxidação de ferro em raízes de dois cultivares de arroz em solução de solo inundado

Nava, Gilberto; Bohnen, Humberto

doi:10.1590/s0100-06832002000200005

Cited by 6 publications

(8 citation statements)

References 7 publications

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“…BR IRGA 409 and Epagri 108 have both iron oxidation ability, suggesting that this ability is not sufficient to explain their different sensitivity to iron (Nava and Bohnen, 2002). Even though RDM was significantly higher in every genotype after 12 DUS, RL was not different from control and only EPAGRI 108 presented higher RN.…”

Section: Discussionmentioning

confidence: 93%

“…Thus, a second strategy is well proposed where a mechanism of iron oxidation on root surface can be used by plants to tolerate iron excess (Becker and Asch, 2005). Iron oxidation on root surface can occur through its precipitation asFe 3+ , caused by the oxygen carried from shoots to roots allowing plants to tolerate this stress due to the exclusion of iron from plant cells (Nava and Bohnen, 2002). Plants with iron excluder (that oxidize and retain iron) can develop aerenchyma and a large number of lateral roots (Wu et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

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Research Article Iron excess in rice: from phenotypic changes to functional genomics of WRKY transcription factors.

Viana¹,

Marini²,

Finatto³

et al. 2017

Genet. Mol. Res.

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ABSTRACT. Iron (Fe) is an essential microelement for all living organisms playing important roles in several metabolic reactions. Rice (Oryza sativa L.) is commonly cultivated in paddy fields, where Fe goes through a reduction reaction from Fe 3+ to Fe 2+. Since Fe 2+ is more soluble, it can reach toxic levels inside plant cells, constituting an important target for studies. Here we aimed to verify morphological changes of different rice genotypes focusing on deciphering the underlying molecular network induced upon Fe excess treatments with special emphasis on the role of four WRKY transcription factors. The transcriptional response peak of these WRKY transcription factors in rice seedlings occurs at 4 days of exposition to iron excess. OsWRKY55-like, OsWRKY46, OsWRKY64, and OsWRKY113 are up-regulated in BR IRGA 409, an iron-sensitive genotype, while in cultivars Nipponbare (moderately resistant) and EPAGRI 108 (resistant) the expression profiles of these transcription factors show similar behaviors. Here is also shown that some cis-regulatory elements known to be involved in other different stress responses can be linked to conditions of iron excess. Overall, here we support the role of WRKY transcription factors in iron stress tolerance with other important steps toward finding why some rice genotypes are more tolerant than others.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Research Article Iron excess in rice: from phenotypic changes to functional genomics of WRKY transcription factors.

Viana¹,

Marini²,

Finatto³

et al. 2017

Genet. Mol. Res.

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“…The glass box was filled with soil solution of a previously flooded Albaqualf (Streck et al, 2008) soil with a history of Fe toxicity induction in susceptible cultivars and a stabilized reduction process, with pH = 6.2 and 80 mg L -1 of iron (Fe 2+ ). The soil solution was obtained by a system comprised of a 50 L asbestos box filled with an Albaqualf soil in an advanced stage of chemical reduction (Nava, 1997). The roots remained in the soil solution for a period of four hours so that the oxygen gradient formed between the inner root (aerenchyma) and the soil solution would promote the diffusion of molecular oxygen to the outside of the roots.…”

Section: Iron Plaquementioning

confidence: 99%

“…Each segment received the addition of 1.0 mL of 0.5 mol L -1 HCl and was kept at rest for 24 h to extract the Fe contained in the root, characterizing each replication, for a total of seven replications for each segment and genotype. The concentrations of dissolved Fe in the samples were determined by atomic absorption spectrophotometer (Nava & Bohnen, 2002). From the digitized images, the surface area of the segment was calculated with the software SIARCS v. 3.0 which, together with the Fe concentration in the sample, allows calculation of the distribution of the chemical element in the segment.…”

Section: Iron Plaquementioning

confidence: 99%

Iron oxidation on the surface of adventitious roots and its relation to aerenchyma formation in rice genotypes

Holzschuh

Carlos

Carmona

et al. 2014

Rev. Bras. Ciênc. Solo

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Establishment of the water layer in an irrigated rice crop leads to consumption of free oxygen in the soil which enters in a chemical reduction process mediated by anaerobic microorganisms, changing the crop environment. To maintain optimal growth in an environment without O2, rice plants develop pore spaces (aerenchyma) that allow O2 transport from air to the roots. Carrying capacity is determined by the rice genome and it may vary among cultivars. Plants that have higher capacity for formation of aerenchyma should theoretically carry more O2 to the roots. However, part of the O2 that reaches the roots is lost due to permeability of the roots and the O2 gradient created between the soil and roots. The O2 that is lost to the outside medium can react with chemically reduced elements present in the soil; one of them is iron, which reacts with oxygen and forms an iron plaque on the outer root surface. Therefore, evaluation of the iron plaque and of the formation of pore spaces on the root can serve as a parameter to differentiate rice cultivars in regard to the volume of O2 transported via aerenchyma. An experiment was thus carried out in a greenhouse with the aim of comparing aerenchyma and iron plaque formation in 13 rice cultivars grown in flooded soils to their formation under growing conditions similar to a normal field, without free oxygen. The results indicated significant differences in the volume of pore spaces in the roots among cultivars and along the root segment in each cultivar, indicating that under flooded conditions the genetic potential of the plant is crucial in induction of cell death and formation of aerenchyma in response to lack of O2. In addition, the amount of Fe accumulated on the root surface was different among genotypes and along the roots. Thus, we concluded that the rice genotypes exhibit different responses for aerenchyma formation, oxygen release by the roots and iron plaque formation, and that there is a direct relationship between porosity and the amount of iron oxidized on the root surface.

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“…A cada segmento foi adicionado 1,0 mL de HCl 0,5 mol L -1 e mantido em repouso por 24 h para realizar a extração do Fe contido na raiz, caracterizando cada repetição, num total de sete repetições para cada segmento e genótipo. As concentrações de Fe dissolvido nas amostras foram determinadas por espectrofotômetro de absorção atômica (Nava & Bohnen, 2002 juntamente com a concentração de Fe na amostra, possibilita calcular a distribuição do Fe no segmento.…”

Section: Placa Férricaunclassified

Avaliação da porosidade e placa férrica de raízes de arroz cultivado em hipoxia

Holzschuh

Bohnen

Anghinoni

2010

Rev. Bras. Ciênc. Solo

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RESUMOA alta difusividade do oxigênio em diversos materiais dificulta a criação e, ou, manutenção de um ambiente livre de O 2 . As técnicas utilizadas são pouco eficientes na exclusão do O 2 e, portanto, não expressam a condição do solo alagado. Os objetivos deste trabalho foram desenvolver um método para obtenção de raízes em condição de hipoxia e avaliar a placa férrica e a formação de aerênquima no arroz. Foi criada uma condição de hipoxia semelhante à do solo alagado em tanques de 50 L, explorando a capacidade de difusão do O 2 por meio do vinil em contato com solo reduzido. Cada tanque preenchido com solo (Gleissolo háplico) recebeu cinco sacos de vinil e foi mantido alagado. Plantas dos genótipos IRGA 423 e IRGA 424 previamente cultivadas em campo foram coletadas, tendo as raízes cortadas junto ao colo, lavadas e um terço da lâmina foliar removido. Cada saco de vinil recebeu 12 plantas de cada genótipo e solução nutritiva. Após sete dias, as novas raízes adventícias formadas foram utilizadas na determinação da porosidade e a da placa férrica em segmentos de 0-2, 2-4 e 4-6 cm a partir da ponta da raiz. As raízes foram colocadas em contato com a solução de um solo em processo de redução por 4 h e a placa férrica determinada após a extração do Fe com HCl 0,5 mol L -1 . A porosidade foi determinada pela aplicação de ciclos de vácuo, com auxílio de seringas. A diferença de peso antes e depois do tratamento com vácuo e entrada de água foi assumida como sendo a estimativa da magnitude do aerênquima ao longo da raiz. A eficácia do método foi testada com a produção de raízes adventícias em saco de vinil com aeração e hipoxia. A porosidade nas raízes foi maior em ambiente hipóxico, comparado à aeração. A porosidade foi maior na proximidade da base da planta e, à medida que a porosidade aumentou, houve aumento do conteúdo de Fe na superfície das raízes, indicando que a placa férrica pode servir como estimativa da formação de aerênquima no arroz. O método de obtenção de raízes foi eficiente em promover a eliminação de O 2 do saco de vinil para estudar a formação do aerênquima.Termos de indexação: anaerobiose, Oryza sativa L., aerênquima.

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Oxidação de ferro em raízes de dois cultivares de arroz em solução de solo inundado

Cited by 6 publications

References 7 publications

Research Article Iron excess in rice: from phenotypic changes to functional genomics of WRKY transcription factors.

Research Article Iron excess in rice: from phenotypic changes to functional genomics of WRKY transcription factors.

Iron oxidation on the surface of adventitious roots and its relation to aerenchyma formation in rice genotypes

Avaliação da porosidade e placa férrica de raízes de arroz cultivado em hipoxia

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