Effect of ammonium on nitrate utilization by roots of dwarf bean
BRETELER, H.
Effect of ammonium on nitrate utilization by roots of dwarf bean - 75(4):1099-1103
Se estudio el efecto de NH4+ exogeno en la absorcion de NO3- y en la actividad reductasa in vivo de NO3- (ARN) en raices de Phaseolus vulgaris cv. Witte Krombek, antes, durante y despues de la induccion aparente del ARN de la raiz y de la absorcion de NO3-. no afecto ni el patron Cuando se suministro NH4+ al comienzo de la nutricion con NO3-, el patron de tiempo de absorcion de NO3- fue el mismo que el de plantas que no recibieron NH4+. ARN de la raiz resultaron inhibidos por el NH4+ hasta un max de 45 y 60 por ciento, resp. de la concn. de NH4Cl. inmediatamente y se presento un poco de restauracion durante la segunda hora. Durante la tercera hora, la TAN se volvio constante. de NH4+ de 2 mM y mayores causaron una estimulacion rapida y transitoria de la absorcion de NO3-seguida otra vez por una disminucion en la primera, una recuperacion en la segunda, y un estado fijo en la tercera hora. inhibicion max. de la TAN fija fue del 50 por ciento. con NO3-, el ARN de la raiz respondio menos y mas lentamente al NH4+ que la TAN. glutamato sintasa, resp., mitigaron la inhibicion de la TAN de plantas inducidas con NO3-. depende de la asimilacion de NH4+. los niveles mas bajos y mas altos de NH4+ evaluados (0.04 y 25.00 mM). (RA-CIAT) The effect of exogenous NH4(+) on NO3(-) uptake and in vivo NO3(-) reductase activity (NRA) in roots of Phaseolus vulgaris cv. Witte Krombek was studied before, during, and after the apparent induction of root NRA and NO3(-) uptake. Pretreatment with NH4Cl (0.15-50.00 mm) affected neither the time pattern nor the steady state rate of NO3(-) uptake. When NH4(+) was given at the start of NO3(-) nutrition, the time pattern of NO3(-) uptake was the same as in plants receiving no NH4(+). After 6 h, however, the NO3(-) uptake rate (NUR) and root NRA were inhibited by NH4(+) to a max. of 45 and 60 percent, resp. The response of the NUR of NO3(-)- induced plants depended on the NH4Cl concn. Below 1 mM NH4(+), the NUR declined immediately and some restoration occurred in the 2nd hour. In the 3rd hour, the NUR became constant. In contrast, NH4(+) at 2 mM and above caused a rapid and transient stimulation of NO3(- ) uptake, followed again by a decrease in the 1st, a recovery in the 2nd, and a steady state in the 3rd hour. Maximal inhibition of steady state NUR was 50 percent. With NO3(-)-induced plants, root NRA responded less and more slowly to NH4(+) than did NUR. Met. sulfoximine and azaserine, inhibitors of glutamine synthetase and glutamate synthase, resp., relieved the NH4(+) inhibition of the NUR of NO3(-)-induced plants. It was concluded that repression of the NUR by NH4(+) depends on NH4(+) assimilation. The repression by NH4(+) was least at the lowest and highest NH4(+) levels tested (0.04 and 25.00 mM). (AS)
Phaseolus vulgaris
Nutrient uptake
Roots
DWARF BEANS
N
Netherlands
Fertilizers
Nutritional requirements
Cultivation
PLANT ASSIMILATION
PLANT PHYSIOLOGICAL PROCESSES
Plant physiology
Physiology
Plant habit
MINERALS AND NUTRIENTS
Europe
Agronomic characters
Plant anatomy
Phaseolus vulgaris
Frijol Beans Journal articles ArtÃculos en revistas Electronic documents Documentos electrónicos Journal article
25195
Effect of ammonium on nitrate utilization by roots of dwarf bean - 75(4):1099-1103
Se estudio el efecto de NH4+ exogeno en la absorcion de NO3- y en la actividad reductasa in vivo de NO3- (ARN) en raices de Phaseolus vulgaris cv. Witte Krombek, antes, durante y despues de la induccion aparente del ARN de la raiz y de la absorcion de NO3-. no afecto ni el patron Cuando se suministro NH4+ al comienzo de la nutricion con NO3-, el patron de tiempo de absorcion de NO3- fue el mismo que el de plantas que no recibieron NH4+. ARN de la raiz resultaron inhibidos por el NH4+ hasta un max de 45 y 60 por ciento, resp. de la concn. de NH4Cl. inmediatamente y se presento un poco de restauracion durante la segunda hora. Durante la tercera hora, la TAN se volvio constante. de NH4+ de 2 mM y mayores causaron una estimulacion rapida y transitoria de la absorcion de NO3-seguida otra vez por una disminucion en la primera, una recuperacion en la segunda, y un estado fijo en la tercera hora. inhibicion max. de la TAN fija fue del 50 por ciento. con NO3-, el ARN de la raiz respondio menos y mas lentamente al NH4+ que la TAN. glutamato sintasa, resp., mitigaron la inhibicion de la TAN de plantas inducidas con NO3-. depende de la asimilacion de NH4+. los niveles mas bajos y mas altos de NH4+ evaluados (0.04 y 25.00 mM). (RA-CIAT) The effect of exogenous NH4(+) on NO3(-) uptake and in vivo NO3(-) reductase activity (NRA) in roots of Phaseolus vulgaris cv. Witte Krombek was studied before, during, and after the apparent induction of root NRA and NO3(-) uptake. Pretreatment with NH4Cl (0.15-50.00 mm) affected neither the time pattern nor the steady state rate of NO3(-) uptake. When NH4(+) was given at the start of NO3(-) nutrition, the time pattern of NO3(-) uptake was the same as in plants receiving no NH4(+). After 6 h, however, the NO3(-) uptake rate (NUR) and root NRA were inhibited by NH4(+) to a max. of 45 and 60 percent, resp. The response of the NUR of NO3(-)- induced plants depended on the NH4Cl concn. Below 1 mM NH4(+), the NUR declined immediately and some restoration occurred in the 2nd hour. In the 3rd hour, the NUR became constant. In contrast, NH4(+) at 2 mM and above caused a rapid and transient stimulation of NO3(- ) uptake, followed again by a decrease in the 1st, a recovery in the 2nd, and a steady state in the 3rd hour. Maximal inhibition of steady state NUR was 50 percent. With NO3(-)-induced plants, root NRA responded less and more slowly to NH4(+) than did NUR. Met. sulfoximine and azaserine, inhibitors of glutamine synthetase and glutamate synthase, resp., relieved the NH4(+) inhibition of the NUR of NO3(-)-induced plants. It was concluded that repression of the NUR by NH4(+) depends on NH4(+) assimilation. The repression by NH4(+) was least at the lowest and highest NH4(+) levels tested (0.04 and 25.00 mM). (AS)
Phaseolus vulgaris
Nutrient uptake
Roots
DWARF BEANS
N
Netherlands
Fertilizers
Nutritional requirements
Cultivation
PLANT ASSIMILATION
PLANT PHYSIOLOGICAL PROCESSES
Plant physiology
Physiology
Plant habit
MINERALS AND NUTRIENTS
Europe
Agronomic characters
Plant anatomy
Phaseolus vulgaris
Frijol Beans Journal articles ArtÃculos en revistas Electronic documents Documentos electrónicos Journal article
25195