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Photoinhibition of stem elongation by blue and red light: effects on hydraulic and cell wall propertiesThe underlying mechanism of photoinhibition of stem elongation by blue (BL) and red light (RL) was studied in etiolated seedlings of pea (Pisum sativum L. cv Alaska). Brief BL irradiations resulted in fast transient inhibition of elongation, while a delayed (lag approximately 60 minutes) but prolonged inhibition was observed after brief RL. Possible changes in the hydraulic and wall properties of the growing cells during photoinhibition were examined. Cell sap osmotic pressure was unaffected by BL and RL, but both irradiations increased turgor pressure by approximately 0.05 megapascal (pressure-probe technique). Cell wall yielding was analyzed by in vivo stress relaxation (pressure-block technique). BL and RL reduced the initial rate of relaxation by 38 and 54%, while the final amount of relaxation was decreased by 48 and 10%, respectively. These results indicate that RL inhibits elongation mainly by lowering the wall yield coefficient, while most of the inhibitory effect of BL was due to an increase of the yield threshold. Mechanical extensibility of cell walls (Instron technique) was decreased by BL and RL, mainly due to a reduction in the plastic component of extensibility. Thus, photoinhibitions of elongation by both BL and RL are achieved through changes in cell wall properties, and are not due to effects on the hydraulic properties of the cell.
Document ID
20040090428
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kigel, J.
(The Hebrew University of Jerusalem Rehovot, Israel)
Cosgrove, D. J.
Date Acquired
August 21, 2013
Publication Date
January 1, 1991
Publication Information
Publication: Plant physiology
Volume: 95
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Report/Patent Number
ISSN: 0032-0889
Funding Number(s)
CONTRACT_GRANT: DE-0284ER13179
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Space Biology
Non-NASA Center
NASA Discipline Plant Biology
NASA Discipline Number 40-50
Peas/cytology/growth & development/radiation effects
Plant Stems/cytology/growth & development/radiation effects
Light
Cell Wall/physiology
Stress, Mechanical
Support, U.S. Gov't, P.H.S
Biomechanics
Osmotic Pressure
Support, U.S. Gov't, Non-P.H.S

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