Document Detail

Interaction of xylem and phloem during exudation and wound occlusion in Cucurbita maxima.
MedLine Citation:
PMID:  22765252     Owner:  NLM     Status:  Publisher    
Collection of cucurbit exudates from cut petioles has been a powerful tool for gaining knowledge on phloem-sap composition without full notion of the complex exudation mechanism. Only few publications explicitly mentioned that exudates were collected from the basal side of the cut which exudes more copiously than the apical side. This is surprising since only exudation from the apical side is supposedly driven by phloem-pressure gradients. Composition of carbohydrates and pH-values at both wounding sides are equal, whereas protein concentration is higher at the basal side. Apparently, exudation is far more complex than just the delivery of phloem sap. Xylem involvement is indicated by lower protein concentrations after elimination of root pressure. Moreover, dye was sucked into xylem vessels owing to relaxation of negative pressure after cutting. The lateral water efflux from the vessels increases turgor of surrounding cells including sieve elements. Simultaneously, detached parietal proteins (PP1/PP2) induce occlusion of sieve plates and cover wound surface. If root pressure is strong enough, pure xylem sap can be collected after removal of the occlusion plug at the wound surface. The present findings provide a mechanism of sap exudation in Cucurbita maxima, in which the contribution of xylem water is integrated. © 2012 Blackwell Publishing Ltd.
Matthias R Zimmermann; Jens B Hafke; Aart J E van Bel; Alexandra C U Furch
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-5
Journal Detail:
Title:  Plant, cell & environment     Volume:  -     ISSN:  1365-3040     ISO Abbreviation:  -     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-7-6     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9309004     Medline TA:  Plant Cell Environ     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2012 Blackwell Publishing Ltd.
Institute for Phytopathology and Applied Zoology, Heinrich-Buff-Ring 26-32, D-35392 Gießen Department of Cell Biology, Institute for General Botany, Senckenbergstrasse 17, D-35390 Gießen Plant Cell Biology Research Group, Institute for General Botany, Senckenbergstrasse 17, D-35390 Gießen.
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