Temporal effect of 2,4-D on induction of embryogenic nuclellar cultures and somatic embryo development of ‘Carabao’ mango

Summary

Embryogenic nucellar cultures were established on B5 major salts, MS minor salts and organics, 400 mg/l⁻¹ glutamine, 60 g/l⁻¹ sucrose, 2 g/l⁻¹ gellan gum, and 4.5 µM 2,4-dichlorophenoxyacetic acid (2,4-D). There was no clear relationship between developmental age of the nucellar explants and induction of embryogenic cultures. The temporal requirements for culture initiation and for induction of embryogenic competence from nucellar explants were determined by pulsing the cultures for 0, 7, 14, 21, 28, 35, 42, 49, 56, and 63 d. Culture initiation required a minimum 7–14 d pulse with 2,4-D, and was maximum after a 56-d pulse; however, embryogenic competence was optimum after a minimum of 28 d exposure to 2,4-D. Somatic embryogenesis occurred directly from the nucellar explants at low frequencies. Somatic embryo maturation only occurred following plating of suspensions onto semisolid medium, and was stimulated by 2.4–4.8 µM kinetin and 4.4 µM 6-benzyladenine.