Influence of plant growth regulators on some enzymes of nitrogen assimilation in mustard seedlings

Effect of plant growth regulators (PGR) viz. gibberellic acid (GA), kinetin (KN), and abscissic acid (ABA) were investigated on growth and activities of nitrate reductase (NR) and glutamine synthetase (GS) in mustard (Brassica juncea) seedlings. All the PGRs tested promoted in vivo NR activity in co...

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Bibliographic Details
Published in:Journal of plant nutrition 1998-01, Vol.21 (8), p.1765-1777
Main Authors: Chanda, S.V. (Saurashtra University, Rajkot, India.), Sood, C.R, Reddy, V.S, Singh, Y.D
Format: Article
Language:English
Subjects:
ABA
ABSORCION DE SUSTANCIAS NUTRITIVAS
ABSORPTION DE SUBSTANCES NUTRITIVES
ACIDO GIBERELICO
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
Agronomy. Soil science and plant productions
AZOTE
Biological and medical sciences
BRASSICA JUNCEA
CITOPLASMA
COTILEDONES
COTYLEDON
COTYLEDONS
CYTOPLASM
CYTOPLASME
CYTOSOL
Economic plant physiology
ENZYMIC ACTIVITY
Fundamental and applied biological sciences. Psychology
GIBBERELLINE
GLUTAMATE-AMMONIA LIGASE
Growth and development
Growth regulators
HIPOCOTILOS
HYPOCOTYLE
HYPOCOTYLS
KINETIN
KINETINE
LIGASAS
LIGASE
LIGASES
NITRATE REDUCTASE
NITRATO REDUCTASA
NITROGEN
NITROGENO
NUTRIENT UPTAKE
QUINETINA
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Summary:Effect of plant growth regulators (PGR) viz. gibberellic acid (GA), kinetin (KN), and abscissic acid (ABA) were investigated on growth and activities of nitrate reductase (NR) and glutamine synthetase (GS) in mustard (Brassica juncea) seedlings. All the PGRs tested promoted in vivo NR activity in cotyledons, but the magnitude differed with different treatments. Cytosolic GS in root and hypocotyl was promoted by GA treatment and inhibited by ABA and KN treatments although the latter showed slight promotion initially in hypocotyl; the trend was not clear in cotyledons. Determination of K(m) value of GS extracted from 96-h-old cotyledons recorded lower K(m) value in GA treatment (2.5 mM), while it increased in ABA treatment (4.35 mM). There was little change in K(m) value in KN (3.03 mM) treatment. The kinetics of GS enzyme in cotyledons of different treatments showed marked variation in V(max). Both GA and ABA treatments inhibited GS activity while no significant effect by KN treatment was observed. It is argued that GA treatment inhibits chloroplastic GS (an enzyme which has higher K(m) value), while ABA-induced inhibition may not be specific to cytosolic or chloroplastic isoforms. Kinetin treatment was ineffective in promoting or inhibiting GS activity in cotyledons. The above conclusion is further supported by chloroplastic pigment data where inhibition is recorded in all the PGRs tested
ISSN:0190-4167
1532-4087
DOI:10.1080/01904169809365521