Polyamines and nucleic acids during the first cell cycle of Helianthus tuberosus tissue after the dormancy break.

Polyamines (spermine, spermidine, and putrescine) and nucleic acids were studied during the first cell cycle after the break of dormancy of tuber slices of Helianthus tuberosus L., cv. OB1. Immediately after the break of dormancy, a marked decrease in stored arginine and glutamine and a corresponding increase of polyamines were observed. This first synthesis of polyamines were observed. This firs synthesis of polyamines occurred very early during the G1 phase, concomitant to the synthesis of RNAs. A RNA, probably messenger-like RNA, was synthesized very actively only during the first hours of activation in the culture medium plus 2,4-dichlorophenoxyacetic acid, or in water. At the onset of the S phase, after 12h of activation, an incorporation of [(3)H] thymidine was also detected. A second putrescine synthesis and polyamine accumulation began during the progression of the S phase. During the progression of mitosis, there was a decrease of polyamine synthesis and accumulation.