ROLE AND METABOLISM OF ABSCISIC-ACID IN POTATO-TUBER DORMANCY AND SPROUTING

Tubers cv. Monalisa were analysed to determine the content of abscisic acid (c-t-(+)ABA) and related metabolites in three tuber parts (eyes, sub-eye tissues and pith). Analyses were performed from the last peri od of tuber growth until sprouting under two different storage tempera tures (3 degrees C and 23 degrees C). ABA content rises in eyes and su b-eye tissues as sprouting approaches, regardless of storage temperatu re. Dihydrophaseic acid is the main ABA metabolite while phaseic acid was not detected, probably because of its further metabolization to DP A. ABA-glucose ester concentrations are generally low in all tissues e xcept in eyes before harvest. The results are discussed in relation to the current hypotheses on the role of ABA in the control of potato tu ber dormancy.