Brassinosteroid stimulation of hypocotyl elongation and wall relaxation in pakchoi (Brassica chinensis cv Lei-Choi)

Hypocotyl elongation of pakchoi (Brassica chinensis cv Lei-Choi) was stimulated by applying 300 ng of brassinosteroid (2 alpha, 3 alpha, 22 beta, 23 beta-tetrahydroxy-24 beta-methyl-B-homo-7-oxa-5 alpha-cholestan-beta-one, BR) in 1 microliter of 50% ethanol to the apex of hypocotyls. BR had its grea...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1993-03, Vol.101 (3), p.965-968
Main Authors: Wang, T.W, Cosgrove, D.J, Arteca, R.N
Format: Article
Language:English
Subjects:
550800 > Morphology
Agronomy. Soil science and plant productions
ALCOHOLS
Auxins
BASIC BIOLOGICAL SCIENCES
Biological and medical sciences
BIOLOGICAL EFFECTS
BRASSICA
BRASSICA CHINENSIS
Brassinosteroids
CELL CONSTITUENTS
Cell growth
CELL WALL
Cell walls
CELLULE
CELULAS
Chemical agents
CONTROL
CRECIMIENTO
CROISSANCE
Development and Growth Regulation
ELASTICIDAD
ELASTICITE
ELONGATION
ETHANOL
FITOSTEROLES
FOOD
Fundamental and applied biological sciences. Psychology
GROWTH
HIPOCOTILOS
HYDROXY COMPOUNDS
HYPOCOTYLE
Hypocotyls
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MATERIALS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
Osmosis
PARED CELULAR
PAROI CELLULAIRE
PHYTOSTEROL
Plant physiology and development
PLANT STEMS
PLANTS
PLANTULAS
PLANTULE
PRESION OSMOTICA
PRESSION OSMOTIQUE
PROPIEDADES MECANICAS
PROPIEDADES REOLOGICAS
PROPRIETE MECANIQUE
PROPRIETE RHEOLOGIQUE
RELAXATION
SAP
SEEDLINGS
SINTERED MATERIALS
STEROIDS
STIMULATION
VEGETABLES 550200 > Biochemistry
Vegetative apparatus, growth and morphogenesis. Senescence
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Summary:Hypocotyl elongation of pakchoi (Brassica chinensis cv Lei-Choi) was stimulated by applying 300 ng of brassinosteroid (2 alpha, 3 alpha, 22 beta, 23 beta-tetrahydroxy-24 beta-methyl-B-homo-7-oxa-5 alpha-cholestan-beta-one, BR) in 1 microliter of 50% ethanol to the apex of hypocotyls. BR had its greatest effect on elongation of the apical 3-mm region below the cotyledonary node (75% stimulation) between 6 and 18 h after treatment. Stress/strain (Instron) analysis of this 3-mm region revealed that plastic and elastic components of extension were not significantly different between BR-treated and control seedlings. In pressure-block experiments, the initial rate of relaxation was 2-fold faster in BR-treated plants as compared with controls, whereas after 125 min the total amount of relaxation and the relaxation rate were the same for the two treatments. Osmotic pressure of cell sap expressed from this 3-mm region showed a large decrease (28%) in BR-treated seedlings compared to the controls. We conclude that BR stimulates growth in pakchoi by accelerating the biochemical processes that cause wall relaxation, without inducing a large change in wall mechanical properties
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.101.3.965