Decontamination of Melicope explants

Abstract

Melicope is a genus mostly endemic to the Hawaiian Islands. Two of its species, M. anisata and M. paniculata produce berries that are coveted for leis. Although not endangered, Melicope populations have been impacted by wild collection of the fruits. The plants are propagated solely by seeds which take a long time to germinate. Melicope has not been successfully propagated by air layering and cuttings; micropropagation was used to try to obtain plants in vitro. The plants are only found in the wild, which made the plant material extremely hard to decontaminate. In an attempt to obtain sterile explants efficiently, different surface sterilization treatments included ethanol, hydrogen peroxide, sodium hydroxide, Plant Preservative Mixture™ (PPM), soapy water, chlorine gas, and antibiotics such as carbenicillin, amphotericin, streptomycin, and mefenoxam. Chlorine gas was the most effective at producing a high number of clean explants, while the use of PPM and antibiotics also gave good results. The explant type that had the highest decontamination rate were the microcuttings, which were also the tissues that were the most responsive in vitro. These finding may lead to a successful protocol for further research in the micropropagation of Melicope.