Loss of tomato cell wall galactan may involve reduced rate of synthesis

Changes in the galactose content of the noncellulosic polysaccharides of tomato (Mill) fruit cell walls were analyzed under various conditions. On the plant, galactan decreased gradually during fruit growth. As normal fruits ripened, the loss of galactan increased sharply; this was not observed in attached rin fruits beyond the fully mature stage. The ability to produce new wall galactan in vitro was retained in mature fruit tissue but declined with ripening. Normal tomatoes ripening on the plant showed a transient increase in galactan content at the climacteric. It is suggested that the decline in wall galactan is partly due to reduced synthesis in senescing, normal fruits and in detached rin tomatoes.