Comparative Evaluation of Biochemical Responses of Callus Cultures of Cichorium endivia L. and Cichorium intybus L. to In vitro Salinity Stress

In this study, the responses of callus cultures of Cichorium endivia L. and Cichorium intybus L. to in vitro salt stress (0, 50, 100, and 150mM NaCl) on MS medium were comparatively investigated. Callus morphology (structure and color) and growth parameters (fresh and dry weight) were evaluated alongside key biochemical indicators, including hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents, antioxidant enzyme activities (Superoxide dismutase: SOD, Catalase: CAT, and Peroxidase: POD), and soluble protein levels. Principal component analysis (PCA) and heatmap visualization were applied to elucidate relationships among the measured variables and treatment effects. The results demonstrated that increasing salinity significantly influenced both morphological and biochemical responses, with clear interspecific differences. Cichorium intybus exhibited comparatively higher tolerance, as enhanced CAT and POD activities partially alleviated oxidative stress at moderate salinity levels (50-100mM NaCl). In contrast, C. endivia showed pronounced oxidative stress responses even at lower salt concentrations, and no callus formation was observed at 150mM NaCl. Overall, the findings indicate that C. intybus displays greater salinity tolerance under in vitro conditions, highlighting its potential for future stress physiology and breeding studies.