In Vitro Regeneration of Coconut Plantlets from Immature Inflorescence

Clonal propagation of elite, disease-free coconut palms is a promising technique for producing uniform planting material with high yield and disease resistance. Over the past few decades cloning of coconut has been attempted in a number of laboratories worldwide; however, success has been limited. In the present study, immature inflorescences of 2–12 cm size were collected from West Coast Tall variety and the rachilla segments were cultured on four different media combinations in dark condition. White translucent outgrowths were maximum in Y3 medium supplemented with 4.54 μM 2,4-dichlorophenoxyacetic acid (92%) followed by medium 72 with 41.4 μM picloram, 61.8 μM putrescine and 4.54 μM thidiazuron (TDZ) (87%). After eight weeks in dark, shoot-like outgrowth was noticed more in Y3 III (65%) followed by Y3 I. After eight months dark incubation, the cultures were transferred to 1/2 Murashige and Skoog (MS) with two hormone combinations and high frequency of multiple shoot formation was noticed in 1/2 MS with 5.37 μM naphthalene acetic acid (NAA) and 4.44 μM 6-benzylaminopurine (BAP). Maximum shoot development was observed Y3 medium fortified with 5 μM 2-isopentenyl adenine (2ip) and 5 μM BAP. The individual shoots after development of 3–4 leaves were transferred to 1/2 Y3 medium supplemented with 5.37 μM NAA and 24.6 μM indole-3-butyric acid (IBA), and ischolar_main initiation was observed in 39.28% plantlets. Start codon targeted (SCoT) profiling based on banding pattern of PCR-amplified products confirmed the clonal fidelity of in vitro regenerated coconut plantlets. The study indicates the possibility of developing an in vitro regeneration protocol for coconut using immature inflorescence explants.