Meta-Topolin induced highly efficient plant regeneration from various explants of eggplant (Solanum melongena L.)

Eggplant (Solanum melongena L.) is one of the essential vegetables worldwide, and cultivated genotypes of eggplant suffer from numerous abiotic and biotic stresses. A reproducible and efficient plant regeneration system is crucial for applying molecular breeding methods to overcome the difficulties of conventional breeding programs to improve eggplant germplasm, such as genetic transformation and genome editing techniques. The three explant types, cotyledon, hypocotyl, and leaf, were obtained from two different cultivars, Pusa purple long (PL) and Pusa green round (GR) of eggplant. Three explants were cultivated on media augmented with a variety of cytokinins, including BAP, mT, and ZEA, in different concentrations. The media supplemented with mT at 8.28 µM generated the highest number of shoots, which showed the optimum regeneration efficiency for all three explants in two eggplant genotypes. The cotyledon explants generated the optimum number of shoot buds on the medium amended with low concentrations of BAP (2.22 µM), KIN (2.32 µM), and ZEA (4.56 µM), and mT at 8.28 µM. The mT (8.28 µM) and BAP at 2.22 µM combinations produced 25.8 and 18.3 shoots in PL and GR genotypes, respectively. The addition of various concentrations of IAA (1.43 to 5.71 µM), IBA (1.23 to 4.92 µM), and NAA (1.34 to 5.37 µM) in combination with mT (8.28 µM) were evaluated to find out their role on the induction and proliferation of numerous shoot buds from cotyledon explants of two cultivars of eggplant. The medium augmented with mT (8.28 µM) and IAA (2.85 µM) produced 26.4 shoots and 17.8 shoots in cotyledon explants of PL and GR cultivars, respectively. The optimum rooting efficiency of shoots was recorded on the medium containing the IAA (5.71 µM) and produced complete plantlets. The plantlets showed 100% similarity with their mother plants.