Structure of Pectins and Their Possible Role in Resistance of Cotton to Cotton Blight: Progress Report, 1987

摘要

Pectic polymers are an integral part of the primary cell walls of dicots. A more detailed knowledge of the structure of pectic polymers should allow us to understand better how pectins are involved in cell wall function. Pectins are involved in cell expansion, cell adhesion, disease responses, and perhaps cell differentiation and recognition. We are particularly interested in the role of pectins in resistance to cotton blight. By using a combination of classical chemical and enzymic methods with solvolysis of specific glycosidic linkages with liquid HF and degradation of uronic acids with lithium in ethylenediamine as developed in this laboratory, we will characterize, as fully as possible, two major regions of the pectin polymers of cotton suspension culture cell walls. We will determine the size distribution of the homogalacturonan regions and distribution of methyl esterification and acetylation sites within it. None of these characteristics has been determined yet for a primary cell wall pectin. We will characterize the region that, in sycamore cells, and all of the species we have tested, is a repeating disaccharide of rhamnose and galacturonic acid with sidechains on approximately half of the rhamnose residues. We determined that at least one in three of the galacturonic acid residues are acetylated at O-3. We will characterize the sidechains of this region and look for linkages from it to other cell wall polymers. 4 refs. (ERA citation 12:031822)