Nitrogen metabolism and translocation in soybean plants subjected to root oxygen deficiency

Autor(es)

Oliveira, Halley C. ^[1] ; Freschi, Luciano ^[2] ; Sodek, Ladaslav ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Biol, Dept Biol Vegetal, BR-13083862 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Biociencias, Dept Bot, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Plant Physiology and Biochemistry; v. 66, p. 141-149, MAY 2013.
• Citações Web of Science: 17

Resumo

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 (NO3-)-N-15 and (NH4+)-N-15 in soybean plants (Glycine max L. Merril cv. IAC-23) subjected to root hypoxia. This stress reduced the uptake of (NO3-)-N-15 and (NH4+)-N-15 from the medium and decreased the overall assimilation of these nitrogen sources into amino acids in roots and leaves. Root (NO3-)-N-15 assimilation was more affected by hypoxia than that of (NH4+)-N-15, resulting in enhanced nitrite and nitric oxide release in the solution. However, (NO3-)-N-15 was translocated in substantial amounts by xylem sap and considerable (NO3-)-N-15 assimilation into amino acids also occurred in the leaves, both under hypoxia and normoxia. By contrast, (NH4+)-N-15 assimilation occurred predominantly in roots, resulting in accumulation of mainly N-15- alanine in this tissue during hypoxia. Analysis of lactate levels suggested higher fermentation in roots from NH4+-treated plants compared to the NO(3)(-)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. (C) 2013 Elsevier Masson SAS. All rights reserved. (AU)

• Processo FAPESP: 09/17583-3 - Efeito benéfico do nitrato na tolerância da soja [Glycine max (L.) Merril] à deficiência de oxigênio: análise do envolvimento do nitrito e do radical óxido nítrico nesse processo
• Beneficiário: Halley Caixeta de Oliveira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado