CHANGES IN POLYAMINE CONTENT DURING DORMANCY IN FLOWER BUDS OF ANNA APPLE

Polyamine, putrescine, spermidine, and spermine contents were determined during endodormancy in the buds of low-chilling-requiring 'Anna' apples (Malus domestica Borkh.). Putrescine, spermidine, and spermine contents increased greatly in buds when their chilling requirement was satisfied. Polyamine biosynthetic inhibitors alpha-difluoromethylarginine (DFMA) or alpha-difluoromethylornithine (DFMO) reduced bud break and bud growth in concert with decreased polyamine titers. DFMO or DFMA did not inhibit bud break when it was applied to buds after they received the full chilling requirement. DFMO was more inhibitory than DFMA. The polyamine requirement was much higher for bud growth and bud development than during differentiation and bud break.