Evaluation of The Genetic and Morphological Diversity of Selected Potato Clones Regenerated from Callus

This research was carried out in the laboratories of the National Commission for Biotechnology (NCBT) and the Faculty of Agriculture (Damascus/Syria) during the years 2018-2020. It aimed to do the morphological and molecular evaluation of eighteen selected potatoregenerated from the callus cultivars exposed to salt stress in vitro.some morphological indicators of these clones were evaluated in the pots, such as the average plant height, which showed a great variation between the clones, in which the experimental values ranged from (88 to 17.08 cm), and the average number of the main branches, which values ranged from 3.83 to 0.83 branches, as for the average number of tubers ,their weight, and their diameter ranged from (0.75 to 6 tubers), (1.91 to 10.33 g), (11.9 to 31.30 mm), respectively. On the other hand, the s7 and s8 clones did not give any tubers.in the field, as a result of the death and withering of some clones, the number of cultivated clones decreased from 16 to 11 clones only, also some morphological studied, such as the average of Emergence percentage, which were taken 20 days after planting showed significant differences between the clones. The experimental values ranged from (2.67 to 100%), and as for the average plant height, the values also showed significant differences ranging from (116 to 23.33 cm), and as for the average number of leaves and leaf area , the values ranged from (12.67 to 94 leaves), and (20.64 to 94.41 cm2), respectively. Also, the average wet weight and dry matter of leaves which represented by the plant were calculated and the values differed from (from 1.25 to 5.26 g) and (from 8.66 to 16.31%), respectively. Then a morphological related tree was established for it using these indicators. the difference and diversity between these clones was attributed to their origin and to the experimental conditions in which planting was carried out, such as lighting, watering times, soil type, and planting date.Then, genetic variances between these clones and their varieties were studied using 12 ISSRs, in which PISSR1 gave the highest morphological polymorphism (66.66%) while PISSR6 gave the lowest morphological polymorphism, and then Dendrogram was studied using ISSR technologyThe research concluded that there are differences and apparent morphological diversity between the studied clones in the potted and in the field, which may be affected by environmental and genetic factors, as some clones showed their superiority in potted and in the field such as the T3 and SF4 clones, and the presence of genetic variances between the studied clones and their varieties, where the highest value was found between the clone s5 and the cultivar svanja was 0.9667, followed by the variation between the clone s7 and the cultivar svanja 0.9660, which indicates a large genetic divergence between them, while the lowest value of the genetic variance was 0.3115 and it was between the strain T2 and T3, followed by the clone S3 and s2 0.3478 and also the two clones sf3 and sf4(0.44) which is low genetic variation between them. The results could be explained by the origin of these clones, as they were selected from callus to three varieties that were subjected to salt stress within a culture medium containing growth regulators, and thus the stage of callus production is a cause of mutations as a result of the continuous divisions of the callus cells to varying degrees, as well as a result of the growth regulators in Cultivation media, in particular 2-4-D, which promotes genetic variation.