Data/hora: 22/09/2024 12:11:54

Biblioteca(s): 	Embrapa Milho e Sorgo.	
Data corrente: 	12/12/2008	
Data da última atualização: 	24/05/2018	
Autoria: 	PURCINO, A. A. C.; LIMA, T. R.; PINTO, A. C.; CARNEIRO, N. P.; SOUZA, I. R. P. de; MARRIEL, I. E.; PARENTONI, S. N.; DURAES, F.; CARVALHO, L.	
Afiliação: 	ANTONIO ALVARO CORSETTI PURCINO, CNPMS; THALES LIMA ROCHA, CENARGEN; NEWTON PORTILHO CARNEIRO, CNPMS; ISABEL REGINA PRAZERES DE SOUZA, CNPMS; IVANILDO EVODIO MARRIEL, CNPMS; SIDNEY NETTO PARENTONI, CNPMS; Frederico Durães, Embrapa Milho e Sorgo; I. Carvalho, bolsista Embrapa Recursos Genéticos e Biotecnologia.	
Título: 	Glutamine synthetase response to nitrate in maize genotypes of contrasting nitrogen use efficiency.	
Ano de publicação: 	2008	
Fonte/Imprenta: 	Maydica, Bergamo, v. 53, p. 101- 109, 2008.	
Idioma: 	Inglês	
Conteúdo: 	Although nitrogen use efficiency (NUE) is a complex trait, recent evidences have indicated that glutamine synthetase (GS, EC 6.3.1.2) is one of its major components. ln maize, GS is encoded by a multigene family and its gene products can be resolved into cytosolic (GSl) and chloroplastic (GS2) isoforms. Therefore, the objective of this study was to determine possible systematic patterns of GS activity or isoenzyme expression response to nitrate nutrition among five maize (Zea mays L.) S5 inbred lines and five single cross hybrids, previously selected for contrasting NUE. Leaf GS biosynthetic activity significantly responded to nitrate nutrition at the 4-leaf seedling and at the 2-day after silking stages, but breeding for increased NUE did not lead to the development of genotypes with increased GS activity. After native polyacrylamide gel electrophoreses (native-PAGE) and staining for transferase activity, GS produced distinct "upper" and "lower" activity bands. ln leaves, these bands did not show a clear nitrate effect pattern, but in roots, the "upper" bands seemed to be more active in high nitrate plants, independently of the NUE of the genotypes tested. Protein gel analysis (SDS-PAGE), however, indicated that breeding for increased NUE, under both low and high nitrate nutrition, led to the development of inbred lines with more GS1 than GS2 Cincreased GS1:GS2 ratio). Except for CMS 28-17.2 under low nitrate, this trend was not observed among the low NUE inbred lines. Altogether, these results suggest that breeding maize inbred lines for better NUE, indirectly selected plants with an increased GS1 content in relation to GS2, without a significant effect on total GS biosynthetic activity. NUE in the single cross hybrids were less influenced by the GS1:GS2 ratio, but one possible explanation for this discrepancy may have been ascribed to the less imense selection pressure for increased NUE undergone by the hybrids.	
Palavras-Chave: 	Glutamine synthetase; Nitrogen use efficiency.	
Thesagro: 	Zea Mays.	
Categoria do assunto: 	S Ciências Biológicas	
Registro original: 	Embrapa Milho e Sorgo (CNPMS)	
Exemplares: 	CNPMS - (21214-1) - UPC - AP - DD -  -  -  - DIS