Alteration in cell wall composition and structure in viroid-infected cells

Abstract

The isolated walls from CEV (citrus exocortis viroid) infected cells have a higher proportion of arabinosyl and galactosyl residues and a lower proportion of xylosyl, mannosyl and glucosyl residues, as well as proteins, than do corresponding walls from healthy cells. These differences become more significant at the early stationary phase of growth. Three kinds of arabinosyl residues and hydroxyproline, indicators of wall extensin, were consistently higher in the walls of CEV-infectcd than in those of healthy tomato cells. It is proposed that arabinogalactans, comprising an undetermined proportion of wall extensin and non-extensin components, are significantly accumulated in the walls of CEV-infected cells to an extent which may impair the wall loosening process. In addition to the implied accumulation of extensin, a greater content of 3-linked glucosyl (2,4,6-tri-O-methyl- D -glucose) residues were detected in the isolated walls of CEV-infected than in those of healthy tomato cells. This change correlates with the specific β-1,3-endoglucanase effect for improved release of protoplasts from CEV-infected, suspension-cultured tomato cells. These composition characteristics may be correlated with fundamental distinctions associated with expansive cell growth and cell surface properties that exist between healthy and CEV-containing tissues.