Polyamines bound to nucleic acids during dormancy and activation of tuber cells of Helianthus tuberosus

Tuber tissue of Helianthus tuberosus L. (cv. OB1) contains a low amount of polyamines during dormancy but they are rapidly synthesized when tuber cells are activated in a growth medium and enter a new cell cycle. It was assumed that one of the reasons for this synthesis is that polyamines are necessary for the active conformation and correct functioning of nucleic acids. Complexes were found between spermine, spermidine and putrescine and rRNA, tRNA and an RNA fraction which contains poly(A) RNA and proteins. The amount of RNA-bound polyamines in the parenchyma cells of dormant tubers is dependent on the stage of dormancy and clearly increases (especially putrescine) when cells are activated. There are both tightly-bound and non-tightlybound polyamines. The significance of these bound polyamines is discussed in relation to their stabilizing role on nucleic acids.