Document Detail

Changes in cell wall biomechanical properties in the xyloglucan-deficient xxt1/xxt2 mutant of Arabidopsis.
MedLine Citation:
PMID:  22108526     Owner:  NLM     Status:  MEDLINE    
The main load-bearing network in the primary cell wall of most land plants is commonly depicted as a scaffold of cellulose microfibrils tethered by xyloglucans. However, a xyloglucan-deficient mutant (xylosyltransferase1/xylosyltransferase2 [xxt1/xxt2]) was recently developed that was smaller than the wild type but otherwise nearly normal in its development, casting doubt on xyloglucan's role in wall structure. To assess xyloglucan function in the Arabidopsis (Arabidopsis thaliana) wall, we compared the behavior of petiole cell walls from xxt1/xxt2 and wild-type plants using creep, stress relaxation, and stress/strain assays, in combination with reagents that cut or solubilize specific components of the wall matrix. Stress/strain assays showed xxt1/xxt2 walls to be more extensible than wild-type walls (supporting a reinforcing role for xyloglucan) but less extensible in creep and stress relaxation processes mediated by α-expansin. Fusicoccin-induced "acid growth" was likewise reduced in xxt1/xxt2 petioles. The results show that xyloglucan is important for wall loosening by α-expansin, and the smaller size of the xxt1/xxt2 mutant may stem from the reduced effectiveness of α-expansins in the absence of xyloglucan. Loosening agents that act on xylans and pectins elicited greater extension in creep assays of xxt1/xxt2 cell walls compared with wild-type walls, consistent with a larger mechanical role for these matrix polymers in the absence of xyloglucan. Our results illustrate the need for multiple biomechanical assays to evaluate wall properties and indicate that the common depiction of a cellulose-xyloglucan network as the major load-bearing structure is in need of revision.
Yong Bum Park; Daniel J Cosgrove
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-11-22
Journal Detail:
Title:  Plant physiology     Volume:  158     ISSN:  1532-2548     ISO Abbreviation:  Plant Physiol.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-03     Completed Date:  2012-07-10     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  465-75     Citation Subset:  IM    
Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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MeSH Terms
Arabidopsis / cytology*,  drug effects,  genetics
Cell Wall / chemistry*,  drug effects
Glucans / genetics*,  metabolism
Glycosides / pharmacology
Pectins / chemistry
Pentosyltransferases / genetics
Plant Proteins / metabolism,  pharmacology
Stress, Mechanical
Xylans / chemistry,  genetics*,  metabolism
Reg. No./Substance:
0/Glucans; 0/Glycosides; 0/Pectins; 0/Plant Proteins; 0/Xylans; 0/expansin protein, plant; 20108-30-9/fusicoccin; 37294-28-3/xyloglucan; EC 2.4.2.-/Pentosyltransferases; EC xylose-protein xylosyltransferase

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