Data/hora: 30/05/2024 02:29:15

Biblioteca(s): 	Embrapa Soja.	
Data corrente: 	18/11/1992	
Data da última atualização: 	27/10/2004	
Autoria: 	HARPER, J. E.	
Afiliação: 	USDA/ARS and Department of Agronomy, University of Illinois, Urbana, Illinois 61801, USA.	
Título: 	Nitrogen metabolism mutants of soybean.	
Ano de publicação: 	1989	
Fonte/Imprenta: 	In: CONFERENCIA MUNDIAL DE INVESTIGACION EN SOJA, 4., 1989, Buenos Aires. Actas... Buenos Aires: AASOJA, 1989.	
Volume: 	t.1	
Páginas: 	p.212-216.	
Idioma: 	Inglês	
Conteúdo: 	The inhibitory effect of NO3- on nodulation of soybean, Glycine max (L.) Merr., has been well established. A mutation approach to alter nodulation response to NO3- has been under-taken. Mutagenized seed were screened in the M2 generation for altered nitrate reductase (NR) activity (chlorate toxicity and in vivo NR assay), for increased nodulation when cultured on NO3- (visual selection), and for nonnodulating mutants. Three NR mutants were isolated and biochemically characterized. One mutant, designated nr1, lacks both the NADH and the NADPH constitutive NR activities. Two additional mutants kack only the NADPH constitutive NR activity. All three mutants retain the substrate-inducible NR enzyme and exhibit normal NO3- uptake and metabolism profiles. This indi-cates that the substrate-inducible NR enzyme is sufficiently active to metabolize all incoming NO3-. The NADPH-dependent constitutive NR enzyme was shown to be capable of further reducing nitrite to nitric oxide under experimental conditions (NO2- accumulation in the tissue). Since NO2- does not accumulate under normal growth conditions, this pathway appears unimportant to intact plants. The function of the constitutive NR isoforms remains unknown. Nodulation was normal in all three NR mutants indicating that presence of constitutive NR isoforms is not related to nodulation control. Three mutants have also been selected which exhibit increased nodulation capability in either the absence or presence of NO3-. These mutants appear to be altered in the autoregula-	
Palavras-Chave: 	EUA; Soybean; USA.	
Thesagro: 	Fixação de Nitrogênio; Metabolismo; Nodulação; Soja.	
Thesaurus Nal: 	metabolism; nitrogen fixation; nodulation.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Soja (CNPSO)