The studuy of Auxin and Cytokinin changes and somaclonal variation in regenerated plant and callus of tobacco (Nicotiana rustica L.)

Auxin and cytokinin are two phytohormones which are effective for various vital processes such as plant growth, development and coordinating the responses to the environmental stimuli. It has been argued that these two phytohormones can affect the process of organogenesis by balancing each other's level. The MS medium including 2 mg/lit of BAP hormone and the MS culture medium including 1 mg/lit of NAA hormone and 0.05 mg/lit of Kenitine hormone were respectively used as media for regeneration and callus formation of the tobacco explants. The amounts of Auxin and cytokinin were estimated in the first, second and third months after regeneration in the new shoots and the first generation callus respectively. The results of the above analyses revealed the proportion of Auxin to cytokinin in the time span of three months and this proportion confirmed the quick and preventing effects of auxin in early stages of growth on synthesis and amount of cytokinin. However, the preventing effects of cytokinin on auxin are slow and are probably through managing and changing other developmental processes. In addition, the amount of auxin and cytokinin in callus was lower compared with the amount of it in the control plant. This can be due to the fact that the cells of the callus are not distinctive and are different from the cells of the leafs which have compartment and different sources for the synthesis of hormone, in fact, the only available hormonl source for calluses is the one provided in the culture medium.