Document Detail

Phototropic bending of non-elongating and radially growing woody stems results from asymmetrical xylem formation.
MedLine Citation:
PMID:  17407541     Owner:  NLM     Status:  MEDLINE    
Active phototropic bending of non-elongating and radially growing portion of stems (woody stems) has not been previously documented, whereas negative gravitropic bending is well known. We found phototropic bending in woody stems and searched for the underlying mechanism. We inclined 1-year-old Quercus crispula Blume seedlings and unilaterally illuminated them from a horizontal direction perpendicular to ('normal' illumination) or parallel to ('parallel' illumination) the inclination azimuth. With normal illumination, active phototropic bending and xylem formation could be evaluated separately from the negative gravitropic response and vertical deflection resulting from the weight of the seedlings. One-year-old stems with normal illumination bent significantly, with asymmetrical xylem formation towards the illuminated upper surface and side of the stem, whereas those with parallel illumination showed non-significant lateral bending, with asymmetrical xylem formation only on the upper side. A mechanical model was built on the assumption that a bending moment resulted from the asymmetrical xylem formation during phototropic bending of the woody stems. The model fitted the relationship between the observed spatial distributions of the xylem and the observed lateral bending, and thus supported the hypothesis that phototropic bending of woody stems results from asymmetrical xylem formation, as such occurs during gravitropism.
Jun Matsuzaki; Masaya Masumori; Takeshi Tange
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Plant, cell & environment     Volume:  30     ISSN:  0140-7791     ISO Abbreviation:  Plant Cell Environ.     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-04-04     Completed Date:  2007-06-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9309004     Medline TA:  Plant Cell Environ     Country:  United States    
Other Details:
Languages:  eng     Pagination:  646-53     Citation Subset:  IM    
Department of Forest Science, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
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MeSH Terms
Phototropism / physiology*
Plant Stems / growth & development*
Quercus / growth & development*
Seedling / growth & development
Xylem / growth & development*

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