Polyamine Biosynthesis during Vegetative and Floral Bud Differentiation in Thin Layer Tobacco Tissue Cultures

摘要

Levels of putrescine, spermidine and spermine increase when vegetative or floral buds form in cultures derived from surface explants of inflorescences ofNicotiana tabacumL. cv. Wisconsin-38. Concomitantly, the activity of arginine decarboxylase (ADC) rises and that of ornithine decarboxylase (ODC) declines. DL-α-Difluoromethylarginine (DFMA), a specific suicide inhibitor of ADC, inhibits bud initiation, while DL-α-difluoromethylornithine (DFMO), the analogous suicide inhibitor of ODC, does not. On the other hand, DFMO inhibits the subsequent development of newly regenerated floral buds, while DFMA does not. It thus appears that polyamines derived through ADC may be involved in bud initiation, while polyamines derived through ODC are required for subsequent growth and development of such buds. Especially large increases of spermidine are associated with floral bud differentiation, indicating a possible special morphogenetic role for that polyamin