Evaluation and selection of potato varieties (Solanum tuberosum L.) in vitro and study of their tolerance to osmotic stress

The experiments were conducted in the tissue culture laboratory of the National Commission for Biotechnology (NCBT) in Damascus, and at the Faculty of Science - University of Damascus with the aim of evaluating the response of nine introduced potato varieties resulting from in vitro tissue culture (Montereal, Salvador, Synergy, Yalas, Agria, Arizona, Everest, Evora, Hind) to artificial osmotic stress using sorbitol. This was based on some growth indicators and certain biochemical parameters (chlorophyll a and b, total carotenoids, and proline), to determine the cultivars most adapted to osmotic stress. The plants were treated by adding different concentrations of sorbitol (0, 100, 200, 300, 400 mM) to the growth medium. The experiment was designed according to a completely randomized block design, and significant differences were estimated at a 99% confidence level. The nine varieties varied in their response to osmotic stress, with an increase in the level of osmotic stress (sorbitol concentration) in the growth medium causing a significant decline in all growth parameters (plant length, root length, number of leaves and roots) compared to the control, as well as some biochemical traits (chlorophyll molecules types a and b, and carotenoids), and an increase in some biochemical parameters (proline), compared to the control. Cluster analysis based on the total relative values of growth parameters and biochemical parameters showed the distribution of the studied varieties into three groups depending on their tolerance to osmotic stress. The results indicated that the varieties (Yalas and Salvador) are among the tolerant varieties, while the varieties (Arizona, Hind, Synergy) are moderately tolerant, and the varieties (Agria, Everest, Monteral, Evora) are considered sensitive to osmotic stress. The results indicate the possibility of evaluation and selection in the laboratory as a rapid and effective method to explore the genetic variation for osmotic stress tolerance in potatoes.