The effects of salt stress (50, 100, and 150 mM NaCl) on the levels of free, bound, and total polyamines were studied in the leaf tissues of salt-tolerant (Coban) and salt-sensitive (Sanbro) cultivars of sunflower ( Helianthus annuus L.) plants grown for 15 or 25 days under salinity. The amounts of free, acid-soluble bound, and total spermine increased in leaf tissues of sunflower plants subjected to salt stress while the levels of other polyamines decreased or no significant changes occurred. The increase in some PA titers suggests their potential role in overcoming the adverse effect of salinity stress. The salt sensitivity of the sunflower plants was associated with the excessive accumulation of total polyamines in the leaf tissues of salt-sensitive cultivar (Sanbro) under saline condition. The content of other compounds such as proline, protein, and ions (Na + , K + , Cl -, K + /Na + ) in leaf tissue changed depending on salt concentration and the cultivars used.

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SummaryIn the present study effects of the polyamines; putrescine (Put), spermidine (Spd) and spermine (Spm) have been studied on root tip mitosis of Allium cepa L. Root tips of A. cepa were treated with a series of polyamine (PA) concentrations, ranging from 0.01, 1 and 2 mM for 3, 6, 12, 24 and 48 h. The roots were examined in permanent root tip squash preparations stained by the Feulgen technique. This research has confirmed that PAs have various effects on chromosomes. PA concentrations used, generally had a marked mitodepressive effect on mitotic index (MI) but at 6 h treatment of Spm, Spd and Put at all concentrations had increased MI. Polyamines affected the relative duration of each mitotic stage as compared to the control. They also increased frequency of abnormal mitosis.The types of abnormalities induced are: chromosome stickiness, c-metaphase, anaphase and telophase bridges, disturbed chromosomes of anaphase and telophase stages, lagging and forward chromosomes at anaphase and telophase. Binucleate cells and micronuclei formation at interphase cells were also observed.

The levels of endogenous free, bound, and total abscisic acid (ABA) and the changes in dry weight of the mycelium depending on the culture periods were examined in Pleurotus florida (Basidiomycetes) cultured both in shaking and static media. The relationship between ABA production and the growth rate of the fungus was determined. Our findings show that this fungus synthesizes ABA as a secondary metabolite and the maximum total ABA is produced on the 24th day of the growth period in both shaking and static conditions. It was observed that, depending on the culture period, the dry weight of mycelium was enhanced in the primary metabolic phase, while it was constant in the secondary metabolic phase.These results show that there is a negative relationship between growth rate of the fungus and ABA synthesis.

Changes in the content and form of polyamines (PAs) were investigated in shoots of salt-tolerant (Coban) and salt-sensitive (Sanbro) cultivars of sunflower (Helianthus annuus L.) plants grown for 15 or 25 days under salinity stress (50, 100 and 150 mM NaCl). The salt sensitivity of the sunflower plants was associated with the highest accumulation of total PAs in the shoot tissues of the salt-sensitive cultivar under saline conditions. The amounts of free and total spermine increased in shoot tissues of sunflower plants subjected to salt stress, while the levels of other PAs decreased or showed no significant changes. This suggests that spermine plays a potential role in overcoming the adverse effects of salinity stress. The tissue content of other compounds, such as proline, and ions (Na þ , K þ , Cl 7 , K þ /Na þ ) also changed depending on salt concentration and cultivar.