The research will investigate the biochemical and molecular mechanism(s) involved in low temperature acclimation of ripening tomato which include: (1) cell wall composition and associated enzymes, and carbohydrate accumulation; (2) determination of chilling - induced proteins during acclimation in both chilling susceptible and tolerant lines and changes in the transcriptional activity related to acclimation. %%% Chilling injury is a common physiological disorder which occurs upon exposing tropical plants, such as tomato, to low but non- freezing temperatures. Fruits exposed to chilling injury have reduced storage length, as well as quality, due to adverse alterations in ripening process. Acclimation to chilling injury leads to accumulation of new proteins that may be involved in ethylene biosynthesis, cell wall hydrolysis, turnover of pectic fragments, and/or accumulation of carbohydrates which serve as cryoprotectants. The project will emphasize the early stages of acclimation process and mechanisms related to chilling tolerance which are not well characterized.