Investigating the potential of cybridization to enhance salinity tolerance in citrus rootstocks

Cybridization is a plant biotechnology tool used to enhance the salinity tolerance of citrus rootstocks. To assess its efficacy, we used cuttings from six diploid cybrids generated through symmetric fusion, alongside their respective parental lines. The cybrids used in this study were obtained from Citrus deliciosa Ten. (Willow leaf mandarin) fused with different parental genotypes: cyb M (C. deliciosa Ten. + C. macrophylla), cyb 75 (C. deliciosa Ten. + (C. paradisi × Poncirus trifoliata) cv.4475 Citrumelo), cyb LR (C. deliciosa Ten. + C. limonia cv. Rangpur lime), F (C. deliciosa Ten. + C. limonia cv. Rangpur lime), cyb C35 (C. deliciosa Ten. + (C. sinensis × P. trifoliata) cv.C-35 Citrange), and cyb Cd (C. deliciosa Ten. + (C. reticulata × P. trifoliata) cv. Citrandarin) and Poncirus trifoliata. Growth parameters and chloride (Cl⁻) accumulation were evaluated to determine the physiological responses of the plants to increase NaCl concentrations (0, 50, 100, and 150 mM). All parameters showed significant, dose-dependent responses to salinity stress. The cybrids exhibited differential responses to salinity stress compared to their parental lines. Notably, cyb LR, cyb F (W.L.M. + Rangpur lime), and cyb M (W.L.M. + Macrophylla) displayed a tolerant phenotype, indicating that cybridization can confer enhanced salinity tolerance