Effects of advancement on nucleic acids in sugarbeet (Beta vulgaris) seeds

Sugarbeet (Beta vulgaris) seeds which had undergone an advancement treatment germinated more quickly and showed greater germination in a standard test at 9 degrees C than seeds which had been steeped in water. Both treatments included the fungicide, thiram (tetramethyl thiuram disulphide). Advanced seeds also emerged more quickly and showed higher establishment in the field. The levels of extractable high molecular weight (HMW) RNA and DNA from advanced, thiram-steeped and untreated seeds were compared. Advanced seeds contained significantly (P < 0.05) more HMW RNA and DNA than thiram-steeped or untreated seeds. Extractable DNA levels were higher from thiram-steeped seeds than untreated seeds but not significantly so. Cell-cycle studies on advanced seeds demonstrated an increase from 2% to 24% of root-tip nuclei with DNA contents of 4C and above. This indicates that DNA replication occurred during the advancement treatment. There was no evidence of cell division occurring, indicating that: (1) advanced seeds were arrested post-S-phase and (2) the period following DNA synthesis in sugarbeet seeds is desiccation tolerant.