Poster: Cell walls

Abs # 613: Biophysical consequences of remodelling rhamnogalacturonan-I in transgenic plants

Presenter:	Ulvskov, Peter , p.ulvskov@dias.kvl.dk
Authors	Ulvskov, Peter  (A)   Petersson, Sara  (A)   Anders, Karlsson  (B)   Borkhardt, Bernhard  (A)   Skjøt, Michael  (A)
Affiliations:	(A): Biotechnology Group, DIAS, Thorvaldsensvej 40, 1871 Frederiksberg C (B): Department of Dairy and Food Science and Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Rolighedsvej 30
Web Site:	http://www.dias.kvl.dk

Transgenic potato plants modified in their cell wall structure were characterized with regard to biomechanical properties in order to assign functional roles to the particular cell wall polysaccharides that were targeted by the genetic changes. The targeted polymer was rhamnogalacturonan-I, a complex pectic polysaccharide comprised of mainly neutral oligosaccharide side chains attached to a backbone of alternating rhamnosyl and galacturonosyl units. Tuber rhamnogalacturonan I from the two transformed lines was reduced in linear galactans and branched arabinans respectively. Tuber tissue from wildtype and transformants were subjected to uniaxial compression and the force-deflection curves were recorded at different rates of deformation. The pectic matrix is not a main load bearing structure in the walls, and the introduced changes to the pectin structure are quite small. Still the transformants differed in tissue strength and in strain rate dependence. The results lead us to propose that the pectic matrix performs as a viscoelsatic material that pick up stresses in the walls and transmit stress to the cellulose microfibrils.