Changes in free and conjugated IAA during dormancy and sprouting of potatotubers

The time course of free and conjugated indole-3-acetic acid (IAA) concentra tions was investigated in three distinct parts (eyes, subeye tissues and pi th) of potato (Solanum tuberosum L. cultivar Monalisa) tubers, from the las t period of tuber growth to sprouting under two different storage temperatu res (3 and 23 degrees C). The highest levels of both free and conjugated IA A were detected in eyes, which showed a significant increase of the free ho rmone concentration from harvest to the end of dormancy, regardless of stor age temperature. The concentration of conjugates was higher than free IAA i n eyes and subeye tissues at 23 degrees C, while at 3 degrees C conjugates prevailed only in eyes. Present results suggest the involvement of IAA in t he control of potato tuber dormancy.