Salt Stress-Induced Genetic Variation in Calli and Shoot Cultures of Economically Important Stevia Rebaudiana

Stevia rebaudiana is one of the potent members of family Asteraceae and is famous for the synthesis of Steviol glycosides. Recently it is one of the economically important plants with high market demand. Seed infertility and stem cuttings are the major issues in obtaining homogeneous population, therefore, the best alternative is plant cell, tissue and organ culture. Currently, salt stress is one of the major issues worldwide. The overall objective of the current study was to investigate the effect of salt stress (100 mm NaCl) on genetic variation in calli and shoot cultures of S. rebaudiana . Sterilized leaf explants were inoculated on MS media augmented with 2,4-D (2.0 mg/L) and BAP (2.0 mg/L) for callogenesis. Shoots were obtained by using BAP (2.0 mg/L) and GA 3 (0.5 mg/L) after 30 days. Callus and shoots were exposed to salt stress for 30 days. These fresh calli and shoot cultures were analyzed for genetic variation including three genes. 1: Leaf sample UDP glycosyltransferase gene restricted with Sca I 2: Callus sample gene restricted with Sca I 3: Leaf sample UDP glycosyltransferase mRNA restricted with Nco I 4: Callus sample mRNA restricted with Nco I 5: Leaf sample UDP glycosyltransferase mRNA restricted with Dra III 6: Callus sample mRNA restricted with Dra III. Only the callus sample digested with Dra III showed a variation from the mother plant. Others genes did not show any variation. It is concluded that genetic variation occurs in callus which is undifferentiated mass of cells and the variation caused may be due to salt stress. This study further need sequencing to identify the genes responsible for genetic and Somaclonal variation.