Author : Silva, J. de; Verhoeyen, M.E.

Summary : To produce new tomato varieties with improved rheology characteristics resulting in tomato-based products with better texture and mouthfeel, the antisense approach was used to down-regulate endogenous tomato fruit exogalactanase activity. Antisense down-regulation of the tEG 1A gene in tomato resulted in exogalactanase enzyme activity in pink fruit, which was reduced by approximately 80% (to 20% of wild type levels) suggesting that tEG 1A and/or its close homologues encode the major ripening isoform of exo-galactanase. Reduced enzyme activity correlated with a dramatic inhibition of the ripening-associated loss of cell wall galactose (presumably by significantly reducing galactan depolymerisation). Levels of cell wall associated galactose (mol% of total cell wall sugars) in ripe (pink) transgenic fruit were equivalent to levels typically found un unripe (mature green) tomato fruit (25%).