Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/200527
Type: Artigo de periódico
Title: Nitrogen Metabolism And Translocation In Soybean Plants Subjected To Root Oxygen Deficiency.
Author: Oliveira, Halley C
Freschi, Luciano
Sodek, Ladaslav
Abstract: Although nitrate (NO3(-)) but not ammonium (NH4(+)) improves plant tolerance to oxygen deficiency, the mechanisms involved in this phenomenon are just beginning to be understood. By using gas chromatography-mass spectrometry, we investigated the metabolic fate of (15)NO3(-) and (15)NH4(+) in soybean plants (Glycine max L. Merril cv. IAC-23) subjected to root hypoxia. This stress reduced the uptake of (15)NO3(-) and (15)NH4(+) from the medium and decreased the overall assimilation of these nitrogen sources into amino acids in roots and leaves. Root (15)NO3(-) assimilation was more affected by hypoxia than that of (15)NH4(+), resulting in enhanced nitrite and nitric oxide release in the solution. However, (15)NO3(-) was translocated in substantial amounts by xylem sap and considerable (15)NO3(-) assimilation into amino acids also occurred in the leaves, both under hypoxia and normoxia. By contrast, (15)NH4(+) assimilation occurred predominantly in roots, resulting in accumulation of mainly (15)N-alanine in this tissue during hypoxia. Analysis of lactate levels suggested higher fermentation in roots from NH4(+)-treated plants compared to the NO3(-) treatment. Thus, foliar NO3(-) assimilation may be relevant to plant tolerance to oxygen deficiency, since it would economize energy expenditure by hypoxic roots. Additionally, the involvement of nitric oxide synthesis from nitrite in the beneficial effect of NO3(-) is discussed.
Subject: Adaptation, Physiological
Adenosine Triphosphate
Alanine
Ammonium Chloride
Biological Transport
Cell Hypoxia
Culture Media
Gas Chromatography-mass Spectrometry
Nitrates
Nitric Oxide
Nitrogen
Oxygen
Phloem
Plant Leaves
Plant Roots
Quaternary Ammonium Compounds
Soybeans
Xylem
Rights: fechado
Identifier DOI: 10.1016/j.plaphy.2013.02.015
Address: http://www.ncbi.nlm.nih.gov/pubmed/23500717
Date Issue: 2013
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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