Abstract
Chymotrypsin inhibitor I is a protein that can be induced to accumulate in potato leaflets within hr in the light when leaflets are detached from intact plants and supplied with water. This increase in inhibitor I is not accompanied by an increase in all proteins in the detached leaflets. The accumulation is polar, proceeding from the base of the leaflets toward the tip. Low inhibitor I levels can be effectively maintained in detached leaflets by supplying them either water in the dark or solutions of indole acetic acid or 2,4-dichlorophenoxy acetic acid in the light. Inhibitor I from leaflets is not identical to inhibitor I isolated from potato tubers as determined by immunochemical analyses.