18A-12

I. PRABASARI¹, S. Wilson², M.-L. Liao³, and A. Bacic¹. (1) CRC for Bioproducts, School of Botany, Univ. of Melbourne, Grattan Street, Melbourne, 3010, Australia, (2) Cereal Functional Genomics Centre, School of Botany, Univ. of Melbourne, Grattan Street, Melbourne, 3010, Australia, (3) CRC for Bioproducts, School of Botany, Univ. of Melbourne, Grattan Street, Melbourne, 3010, Australia

Despite their important roles in plant cell wall architecture and industry, our understanding of pectin structure and function is incomplete. The availability of carbohydrate-specific probes (antibodies) enables an immunomicroscopy approach to be employed to study the distribution of pectic polysaccharides in plant tissues. Our objective is to map the distribution of the different pectic polysaccharides in the albedo/flavedo tissue of the peel from orange fruit using a series of commercially available pectin monoclonal antibodies. Conventional tissue fixation with 2.5% gluteraldehyde followed by embedding in LR White was used for orange fruit. The fixed samples were labeled with a series of pectin antibodies, and the gold-conjugated secondary antibodies were silver enhanced and identified by light microscopy (LM) to map the pectic polysaccharides at the tissue level. Transmission microscopy (TEM) was used to further explore the labeling pattern at the cellular level. The result showed that homogalacturonan (JIM7 labeling) was found throughout the cell wall, middle lamella, and corners of intercellular spaces of all tissues examined. Rhamnogalacturonan I (CCRC-M1 labeling) was found throughout the cell wall, while galactan (LM5 labeling) was found only within the primary wall but not in the middle lamella. Arabinan (LM6 labeling) was found throughout the cell wall with a pattern different from that of galactan. Immunolocalization results suggested that different types of pectic polysaccharides occur in distinct regions of the orange peel cell wall. These data will be correlated with our current knowledge of the composition of primary dicot cell walls.

Session 18A, Carbohydrate: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana