Exploring indirect somatic embryogenesis and somaclonal variation for propagation of three Coffea arabica L. cultivars

Abstract

The propagation of arabica coffee (Coffea arabica L.) seedlings through indirect primary embryogenesis has significant potential to produce many healthy seedlings relatively quickly. However, there is a concern that plant growth regulators (PGRs) applied in the culture media could result in somaclonal variations. To address this issue, the appropriate concentration of PGR needs to be identified to increase the success of the somatic embryogenesis process of propagation while preventing somaclonal variations. This study aimed to develop a protocol for the propagation of C. arabica through indirect somatic embryogenesis and evaluate somaclonal variation in plantlets derived from somatic embryogenesis, considering the genotype and PGR used. Three cultivars of coffee, i.e., AS2K, S-795, and Sigarar Utang, and two types of PGRs (2,4-D and 2-iP) at different combination concentrations, were used as the factorial experimental design. The concentration of PGRs was 4.52 and 9.04 μM for 2,4 D and 4.93, 9.86, 14.79, 19.72, and 24.65 μM for 2-iP. All combinations were replicated 10 times. The findings revealed that PGRs influenced percentage of callus formation which ranged from 87.02% to 93.81%, while coffee cultivars significantly impacted the development of torpedoes and germination of somatic embryos with the number of torpedoes and germinated somatic embryos were 32.20-94.20 and 21.10-82.20 for ‘AS2K’, 37.90-62.90 and 27.70-50.20 for ‘S-795’, and 39.40-72.00 and 29.60-60.60 for ‘Sigarar Utang’, respectively. Among the PGRs evaluated, the combination of 4.52 μM 2,4-D and 19.72 μM 2-iP demonstrated the highest efficacy with 94.20 torpedoes and 82.20 germinated somatic embryos for ‘AS2K’, whereas 4.52 μM 2,4-D and 14.79 μM 2-iP were preferred for ‘S-795’ and ‘Sigarar Utang’. Furthermore, molecular analysis using 10 SSR primers of the resulting plantlets indicated no evidence of somaclonal variation.