Cell cultures of a tomato hybrid infected with the citrus exocortis viroid (CEVd) display no adverse effects when compared with viroid-free cultures. The growth patterns of the viroid-containing cultures are not only similar to controls but more efficient as judged by longevity and biomass accumulation. Differences in growth characteristics can be accentuated by modification of the incubation temperature and the carbon sources present in the culture media. Supplementing the culture media with arabinose and xylose induced marked differences in growth and revealed the enhanced tolerance of viroid-containing cells to these sugars. Differences in carbohydrate metabolism and turnover are suggested to be responsible for the previously reported differences in the composition and properties of the cell wall. © 1995.