Résumé
Polyploidy is one of the widespread phenomena in plant kingdom, which has a vital role in evolution and speciation of plants and is usually accompanied by significant changes in morphology, cell and organ size, expression patterns of genes, respiration and phtotosynthesis, regeneration ability, fertility, biochemistry and metabolom of plants. Therefore polyploidy, especially tetraploidy, has been widely applied in modification of various characteristics of plants. The diversity of traits resulted by the induction of polyploidy, depends on the genotype and species and therefore is not always useful. Though tetraploidy usually results in fewer seeds and decrease of fertility but in cases where the increase in biomass or concentration of medicinal compounds is of importance, it can be efficiently applied for breeding of medicinal plants. Autotetraploidy doubles the gene dosage and allotetraploidy collects the useful allels of a biosynthetis pathway in a resulted hybrid and therefore may improve the production of secondary metabolites. According to the importance of herbal medicine and increasing demand for medicinally important secondary metabolites in our country, we describe the effects of polyploidy on various characteristics of medicinal plants and the methods of induction and selection of polyploid plants in this
Résumé
Ploidy manipulation is always accompanied by conspicuous changes in morphology and biochemical characteristics in plants. So that it is suggested as a rapid and useful strategy for breeding the quality and quantitative traits related to the secondary metabolite production in medicinal plants. Egyptian henbane is one of the most important sources of tropane alkaloids specially hyoscyamine and a trace of scopolamine. The main objects of this research were study of the stability of ploidy manipulation and its effects on the qualitative and quantitative changes of tropane alkaloid production in Hyoscyamus muticus plant. The stability of ploidy level in autotetraploid plants [that already obtained by colchicine treatment] of Egyptian henbane was investigated by morphological, microscopic and flow cytometry methods. The changes in the production of tropane alkaloid compounds were also analyzed by GC-MS in diploid and tetraploid plants. The results of morphologic, microscopic and flow cytometry methods confirmed the stability of autotetraploidy in Egyptian henbane plant. Tetraploid plants showed a higher potential in production of scopolamine, than diploid ones. Regard to the higher commercial value of scopolamine than other tropane alkaloid coumpounds, Ploidy manipulation can efficiently be used to improve scopolamine production in Hyoscyamus muticus plant