Document Detail

The structure of the phloem - still more questions than answers.
MedLine Citation:
PMID:  22449049     Owner:  NLM     Status:  In-Data-Review    
Long-distance assimilate distribution in higher plants takes place in the enucleate sieve-tube system of the phloem. It is generally accepted that flow of assimilates is driven by an osmotically generated pressure differential, as proposed by Ernst Münch more than 80 years ago. In the period between 1960 and 1980, the pressure flow hypothesis was challenged when electron microscopic images suggested that sieve tubes contain obstructions that would prevent passive flow. This led to the proposal of alternative translocation mechanisms. However, most investigators came to the conclusion that obstructions in the sieve-tube path were due to preparation artifacts. New developments in bioimaging have vastly enhanced our ability to study the phloem. Unexpectedly, in vivo studies challenge the pressure-flow hypothesis once again. In this review we summarize current investigations of phloem structure and function and discuss their impact on our understanding of long-distance transport in the phloem.
Michael Knoblauch; Karl Oparka
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Plant journal : for cell and molecular biology     Volume:  70     ISSN:  1365-313X     ISO Abbreviation:  Plant J.     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-03-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9207397     Medline TA:  Plant J     Country:  England    
Other Details:
Languages:  eng     Pagination:  147-56     Citation Subset:  IM    
Copyright Information:
© 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.
School of Biological Sciences, Washington State University, Pullman, WA, USA Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, UK.
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