Biophysical consequences of remodeling the neutral side chains of rhamnogalacturonan I in tubers of transgenic potatoes.
Two lines of transgenic potato (Solanum tuberosum L.) plants modified in their cell wall structure were characterized and compared to wild type 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 (RG-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 molecules from the two transformed lines are reduced in linear galactans and branched arabinans, respectively. The transformed tuber tissues were found to be more brittle when subjected to uniaxial compression and the side-chain truncation was found to be correlated with the physical properties of the tissue. Interpretation of the force-deflection curves was aided by a mathematical model that describes the contribution of the cellulose microfibrils, and the results lead to the proposition that the pectic matrix plays a role in transmitting stresses to the load-bearing cellulose microfibrils and that even small changes to the rheological properties of the matrix have consequences for the biophysical properties of the wall.
Ulvskov
Peter
P
Biotechnology Group, Danish Institute of Agricultural Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. p.ulvskov@dias.kvl.dk
Wium
Helle
H
Bruce
David
D
Jørgensen
Bodil
B
Qvist
Karsten Bruun
KB
Skjøt
Michael
M
Hepworth
David
D
Borkhardt
Bernhard
B
Sørensen
Susanne Oxenbøll
SO
D007700:Kinetics; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology*; D012212:Rheology; D013045:Species Specificity; D014867:Water / Q000378:metabolism
C042491:rhamnogalacturonan I; D014867:Water; D010368:Pectins