The cytological, antifungal and antimicrobial effects of plant extracts, especially those having medicinal importance, attracted the attention of many investigators, Ohno (1960), noxious plants, Singh and Madhu (1978) studying the antifungal pro perties of 34 flowering plants and Shehab et al. (1978), reporting the cytological effects of water extracts of Achillea fragrantissima.This work represents part III in the survey concerning the cytological effects of medicinal plants growing in Qatar.The water extract of Anastatica hierochuntica L, a folkmedicinal weed is used as antispasmotic. Material and methodsThe concentrations used were 3, 5, 7 and 10% of the original solution prepared as in part I (Shehab 1979). Results and discussionFrom Table 1, it is clear that treatment of Allium cepa roots with the extract, resulted in a drop in the mitotic activity especially in short durations (1 h), in nearly all concentrations.The results showed that the effect of the extract in producing mitotic index decline was an irreversible one, and it is directly proportional to time of treatment, where recovery treatments induced the lowest mitotic indicies (26.2, 23.6 in 3 and 6 h, 5 and 7%). The effect on mitotic index may be ascribed either to blockage of DNA synthesis, or to inhibition of spindle formation.Studying the data of phase index (Table 1) it is obvious that, all treatments ex cept 10% direct treatment reduced prophase percentage, meanwhile the percentage of metaphases and ana-telophases rose over those of the control. The same effect was observed after recovery treatments. So it is now clear that the components of the extract may interfere with or lead to blockage of DNA synthesis rather than retardation of the spindle formation. Where mitotic index depression was not ac companied by lowering the metaphase and ana-telophase percentages.

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EvEral abiotic stresses including salinity impact plant growth and reduce the productivity of many plants and field crops. Plantlets produced in vitro by tissue culture technique offer a direct and fast approach to investigate the mechanism of stress adaptation. The present study estimated the survival percentage of two potato (Solanum tuberosum l.) cultivars (Spunta and valor) under salt stress as abiotic stresses. Some biochemical alterations and ultrastructural responses of plantlets were examined. Moreover, genetic diversity was also studied using raPD technique. The results showed that, with the increase of external stress there was a significant decrease in the survival percentage, significant accumulation of osmoprotectants (proline) and induction of DNa damages. Furthermore, there were closing of stomatal apertures, changes in chloroplast ultrastructure and cell intercellular spaces markedly decreased. additionally, high salt stress (150 and 200mM NaCl) caused complete inhibition of plantlet growth. The present work provides insight view for the adaptation of potato plantlets to salt stress through accumulating of osmoprotectants and change in molecular and ultrastructure traits.

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