Flooding of the root system in soybean: biochemical and molecular aspects of N metabolism in the nodule during stress and recovery.
Amino Acids
; 48(5): 1285-95, 2016 May.
Article
em En
| MEDLINE
| ID: mdl-26825550
ABSTRACT
Nitrogen fixation of the nodule of soybean is highly sensitive to oxygen deficiency such as provoked by waterlogging of the root system. This study aimed to evaluate the effects of flooding on N metabolism in nodules of soybean. Flooding resulted in a marked decrease of asparagine (the most abundant amino acid) and a concomitant accumulation of γ-aminobutyric acid (GABA). Flooding also resulted in a strong reduction of the incorporation of (15)N2 in amino acids. Nodule amino acids labelled before flooding rapidly lost (15)N during flooding, except for GABA, which initially increased and declined slowly thereafter. Both nitrogenase activity and the expression of nifH and nifD genes were strongly decreased on flooding. Expression of the asparagine synthetase genes SAS1 and SAS2 was reduced, especially the former. Expression of genes encoding the enzyme glutamic acid decarboxylase (GAD1, GAD4, GAD5) was also strongly suppressed except for GAD2 which increased. Almost all changes observed during flooding were reversible after draining. Possible changes in asparagine and GABA metabolism that may explain the marked fluctuations of these amino acids during flooding are discussed. It is suggested that the accumulation of GABA has a storage role during flooding stress.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Asparagina
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Glycine max
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Regulação da Expressão Gênica de Plantas
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Nódulos Radiculares de Plantas
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Nitrogênio
Idioma:
En
Revista:
Amino Acids
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Brasil