Chilling-induced changes in the apoplastic solution of tomato pericarp

Low-temperature storage of chilling-sensitive commodities affects membrane function and is likely to induce changes in the apoplastic environment. Mature-green tomato (Solanum lycopersicum L.) fruit were stored at 5 degrees C for 14 d, then transferred to 15 degrees C for an additional 6 d. Low-temperature storage induced acidification and a slight increase in the osmolality of pressure-extracted tomato apoplastic fluid. The apoplastic levels of cations such as K(+), Ca(2+), and Mg(2+) remained constant during low-temperature storage, but decreased upon transfer of fruit to 15 degrees C following low-temperature storage. These changes in apoplastic cations paralleled the changes observed in electrolyte leakage. Apoplastic pH and mineral concentrations were altered in chill-injured fruit, but the small changes observed in osmolality provide evidence against severe membrane dysfunction in chill-injured fruit.