Relationship of Solute Leakage to Solution Tonicity in Fruits and Other Plant Tissues

Although essentially all plant parts and especially thin sections derived from them have been observed to leach solute upon immersion in water (17), fruits have attracted particular attention because of the concept that an increased permeability of the tonoplast may accompany or be a prerequisite of fruit ripening (3, 19, 27). Previously it was shown (9) that exposure to water causes sections of apple tissue to lose solute and water, decrease in their ability to produce ethylene, and undergo an extensive browning reaction. The changes in water content, ethylene production, and polypenolase activity were prevented by inclusion of a high concentration of various organic or inorganic materials in the soaking media, and the present communication demonstrates that solute leakage also is restricted by this condition. In fact, leakage probably is the indirect cause of many of these effects, and it occurs to a significant extent and in a closely similar manner not only in several fruits, but also in other plant tissues.