Assessment of Salt Stress Effects on Growth and Gene Expression in In Vitro Cultured Sesamum orientale L. cv. ‘Gökova’

Soil salinity is a major abiotic stress factor that adversely affects plant growth and productivity. In this study, the responses of the locally important sesame cultivar Sesamum orientale L. cv. ‘Gökova’, traditionally cultivated in the Gökova basin of Muğla, Türkiye, were investigated under in vitro salt stress conditions at both morphological and molecular levels. Shoot tip explants were cultured on Murashige and Skoog (MS) medium containing different NaCl concentrations (0, 50, and 100 mM), with or without activated charcoal, and regeneration performance, shoot development, shoot number, shoot length, and Shoot Formation Capacity (SOKI) indices were evaluated after four weeks of incubation. In addition, relative mRNA expression levels of selected salt stress-associated genes (GST U25-like, acyl-coenzyme A oxidase 2, 2,3-bisphosphoglycerate-independent phosphoglycerate mutase, and GSTL3-like) were analyzed using Real-Time PCR. The results revealed high regeneration capacity across all treatments (86–100%), although medium containing activated charcoal showed reduced shoot formation parameters. Gene expression analyses demonstrated significant regulation of all investigated genes under salt stress, with notable upregulation of GST-related genes, indicating activation of antioxidant defense mechanisms. Overall, the findings suggest that the ‘Gökova’ sesame cultivar maintains substantial morphogenetic competence under saline conditions and exhibits adaptive molecular responses associated with stress tolerance.