Effect of culture media, auxins and genotypes on plantlet regeneration from oil palm (Elaeis guineensis Jacq.) zygotic embryos through somatic embryogenesis

Abstract

Aim: This study evaluated efficient culture media for the regeneration of elite material through somatic embryogenesis from oil palm zygotic embryos. Methodology: For callus induction, zygotic embryos of four elite genotypes (G1-264T, G2-238DX17P, G3-37DX17P and G4-237T) were cultured on three basal media (Y3, MS and N6) with different auxin 2 mg l-1 (Picloram, 2,4-D and Dicamba) combinations. Subculture was made every month for three passages. It evaluated various callus characters. The embryogenic calli from callus induction media were transferred to the embryo maturation medium and subcultured until the polyembryoids formed. For shoot and root formation, somatic embryo clumps were transferred into regeneration media. In-vitro plantlets with well-grown roots were hardened in pots for six weeks and assessed clonal fidelity using polymorphic SSR primers. Results: Among the treatments, calli from N6+2,4-D, Y3+2,4-D and N6+Picloram showed the highest embryogenic callus potential. G4-237T induced more embryogenic calli (32.982) among genotypes, which was on par with G1-264T (24.196). Embryogenic calli grown on N6 media with Dicamba showed the highest proliferation rate (1.141). After 60 days of culture on regeneration media, the highest number of plantlets per somatic embryogenic clump was obtained from G1-264T on N6 media supplemented with Dicamba. Interpretation: Culture media salt concentration showed a significant difference among media by causing perturbations of auxin flow during somatic embryogenesis affecting callus induction, proliferation and plantlet regeneration. This may be useful for standardizing the genotype-specific regeneration media in oil palm.