Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2003
Publication Date: 1/5/2004
Citation: Sabba, R.P., Lulai, E.C. 2003. Immunocytological determination of rhamnogalacturonan and extensin cell wall polymers associated with skin-set. [abstract]. American Journal of Potato Research. 81(1):85-86.
Technical Abstract: The susceptibility of potato tubers to excoriation (skinning injury) during harvest and handling into storage is a widespread problem that results in costly disease, defects and shrinkage. Little is known about the processes responsible for the development of resistance to excoriation. Recently, we identified the specific type of periderm cells and the cell wall fractures responsible for excoriation. We are now determining the biochemical processes within these cell walls that are responsible for the development of resistance to excoriation. Potato periderm consists of three different cell types: phellem, phellogen, and phelloderm. Changes in the phellogen cell walls upon cessation of meristematic activity and periderm maturation are directly responsible for the development of resistance to excoriation. Here we compare immunolabeling of the cell walls of immature and mature periderm for epitopes of the pectin rhamnogalacturonan-I (RG-I) and the structural protein extensin. Immunolabeling with the monoclonal antibody LM5 (reactive with a (1,4)-ß-galactan epitope found in RG-I) increases dramatically in phellogen walls upon maturation of the periderm. Labeling with the monoclonal antibody LM6 (reactive with a (1,5)-¿-L-arabinan epitope found in RG-I) does not change in phellogen walls upon maturation of the periderm. In addition, immunolabeling with the monoclonal antibody LM1 indicates that extensin increases in these cell walls during periderm maturation. These results identify deposition of a specific type of RG-I and extensin in phellogen cell walls as key biochemical processes involved in the inactivation of the phellogen layer as a lateral meristem and in the development of resistance to excoriation in potato tuber. (Poster, physiology)