Apparent Asexual Embryogenesis in Cultured Leaf Sections of Hoya

Abstract

Summary A diallelic experimental design was used to study the degree of callus induction from leaf explants of Hoya carnosa «Compacta» and Hoya carnosa «Rubra» in response to the following growth regulator interactions: 0–57.0 µ M IAA/0–46.0 µ M kinetin; 0–54.0 µ M NAA/0–46.0 µ M kinetin; and 0–40.0 µ M 2,4-D/0–150.0 µ M kinetin. Callus proliferation was obtained only from explants cultured on media containing an auxin. However, optimal callusing of leaf explants was obtained in the presence of 2,4-D and kinetin. Upon secondary culture, apparent asexual embryos developed exclusively from callus initiated on 2,4-D/kinetin primary culture medium. The concentration ratio of 2,4-D and kinetin during primary culture determines the frequency of embryogenic determination. Primary culture treatments conducive to embryo determination were 2.3–5.0 µ M 2,4-D in combination with 2.5–20.0 µ M kinetin.