Document Detail

Light promotion of hypocotyl gravitropism of a starch-deficient tobacco mutant correlates with plastid enlargement and sedimentation.
MedLine Citation:
PMID:  9490754     Owner:  NASA     Status:  MEDLINE    
Dark-grown hypocotyls of a starch-deficient mutant (NS458) of tobacco (Nicotiana sylvestris) lack amyloplasts and plastid sedimentation, and have severely reduced gravitropism. However, gravitropism improved dramatically when NS458 seedlings were grown in the light. To determine the extent of this improvement and whether mutant hypocotyls contain sedimented amyloplasts, gravitropic sensitivity (induction time and intermittent stimulation) and plastid size and position in the endodermis were measured in seedlings grown for 8 d in the light. Light-grown NS458 hypocotyls were gravitropic but were less sensitive than the wild type (WT). Starch occupied 10% of the volume of NS458 plastids grown in both the light and the dark, whereas WT plastids were essentially filled with starch in both treatments. Light increased plastid size twice as much in the mutant as in the WT. Plastids in light-grown NS458 were sedimented, presumably because of their larger size and greater total starch content. The induction by light of plastid sedimentation in NS458 provides new evidence for the role of plastid mass and sedimentation in stem gravitropic sensing. Because the mutant is not as sensitive as the WT, NS458 plastids may not have sufficient mass to provide full gravitropic sensitivity.
S Vitha; M Yang; J Z Kiss; F D Sack
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Plant physiology     Volume:  116     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1999-06-20     Completed Date:  1999-06-20     Revised Date:  2010-09-13    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  495-502     Citation Subset:  S    
The Ohio State University, Department of Plant Biology, Columbus 43210, USA.
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MeSH Terms
Gravitropism / genetics,  physiology,  radiation effects*
Gravity Sensing / physiology
Hypocotyl / genetics,  physiology,  radiation effects*,  ultrastructure
Plants, Toxic
Plastids / physiology,  radiation effects*,  ultrastructure
Starch / deficiency,  genetics,  metabolism*
Time Factors
Tobacco / genetics,  physiology,  radiation effects,  ultrastructure
Reg. No./Substance:
F D Sack / OH St U, Columbus

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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