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

Journal Article · Mon Mar 01 00:00:00 EST 1993 · Plant Physiology; (United States)

OSTI ID:6448700

Wang, Tzannwei; Cosgrove, D J; Arteca, R N ^[1]

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1. Pennsylvania State Univ., University Park (United States)

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-6-one, BR) in 1 [mu]L 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. The authors 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. 19 refs., 3 figs., 1 tab.

• OSTI ID: 6448700
• Journal Information: Plant Physiology; (United States), Vol. 101:3; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BRASSICA
GROWTH
CELL WALL
RELAXATION
PLANT STEMS
ELONGATION
STEROIDS
BIOLOGICAL EFFECTS
CONTROL
ETHANOL
MECHANICAL PROPERTIES
PLANTS
SAP
SEEDLINGS
STIMULATION
ALCOHOLS
CELL CONSTITUENTS
FOOD
HYDROXY COMPOUNDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MATERIALS
ORGANIC COMPOUNDS
SINTERED MATERIALS
VEGETABLES
550200* - Biochemistry
550800 - Morphology