Clonal regeneration of litchi (Litchi chinensis Sonn.) via somatic embryogenesis

Litchi embryogenic cultures were induced from leaflet explants in recent vegetative flushes of mature phase `Brewster' trees on modified B5 medium containing 400 mg L-1 glutamine, 200 mg L-1 casein hydrolysate, 30 g L-1 sucrose, 3 g L-1 gellan gum, 4.52 mu M 2,4-D and 9.30 mu M kinetin. Embryogenic cultures were maintained on semi-solid MS medium supplemented with 4.52 mu M 2,4-D and 0.91 mu M zeatin at 26 1 C in darkness and with 4-5 week subculture intervals. Maturation of somatic embryos occurred in darkness on semi-solid MS medium without plant growth regulators, and fully enlarged somatic embryos germinated. Plantlets were maintained on 60 ml half-strength MS medium with 200 mg L-1 activated charcoal at 26 1 C under a 16h photoperiod provided by cool white fluorescent lights. Plants were successfully transferred to the greenhouse.