No abstract

Immature inflorescences of oil palm (Elaeis guineensis) var. Pisifera were inoculated onto modified MS medium containing 0.3% (w/v) activated charcoal and 475 μM 2,4-D. After 2-3 months of culture, a hard yellow callus proliferated at the base of the shoot-like structures. The high incidence of phenolic oxidation required the use of increased levels of activated charcoal (0.5% w/v) and 2,4-D (500 μM). Development of floral structures from inflorescence expiants was frequently observed during the culture period. After 81 weeks of culture, an embryogenic tissue characterized by compact consistency and pearly white color was observed in tissues derived from very young inflorescences. This compact embryogenic tissue differentiated into normal somatic embryos when transferred onto regeneration medium containing NAA (15 μM) and ABA (2 μM). Normal plantlets were recovered from these somatic embryos after 8 weeks on regeneration medium.

Immature zygotic embryos at different developmental stages were used for callus induction and regeneration studies. Immature embryos excised from fruits 77, 91, 100, 114, 128, 140 and 193 days after pollination and mature embryos were cultured on modified Y3 medium containing 500 mg 1 -~ cysteine, 0.5% (w/v) PVP-40, 500 p~M 2,4-D and 0.3% (w/v) charcoal. Compact embryogenic tissue began differentiating directly from embryo explants after 2 weeks of culture. The percentage of embryos forming compact embryogenic tissue ranged from 28.6% for 91-day-old embryos to 0% for 140-day-old and older embryos. Friable embryogenic tissue was observed in callus cultures derived from 100-day-old embryos. Although both compact and friable embryogenic tissues were successfully isolated, normal embryo and plantlet development was observed only from friable embryogenic tissue.Abbreviations: ABA-abscisic acid, 2,4-D-2,4-dichlorophenoxyacetic acid, NAA-naphthaleneacetic acid, PVP -polyvinylpyrollidone

Primary globular callus from immature zygotic embryos and friable embryogenic tissue derived from mature zygotic embryos were used to establish suspension cultures. Callus cultures were established either on modified Y3 or MS medium containing 475-500 ttM 2,4-D or 250 paVl picloram and 0.3% (w/v) activated charcoal. Suspension cultures of both cell lines were established in modified Y3 medium containing 10 ~aM 2,4-D. The establishment of cell suspensions from friable embryogenic tissue took only 2 months, in contrast with suspensions from primary globular callus which took 3-5 months to establish. Embryo differentiation was observed only in cell suspensions derived from the friable embryogenic tissue after plating aliquots on regeneration medium. Germinated embryos were recovered and plantlets were successfully established under greenhouse conditions.