Indirect and direct somatic embryogenesis from aerial stem explants of ginger (Zingiber officinale Rosc.)

Abstract

Protocols for direct and indirect somatic embryogenesis from aerial stem explants of ginger have been developed. Aerial stem explants of two ginger varieties were cultured on different concentrations of 2,4-D induced callus. An in vitro aerial stem produced hard, nodular and yellowish callus (Type I) and an in planta aerial stem gave rise to soft, sticky callus with pale white color (Type II). The proliferated Type II calli were subject to stress for 40–60 days without subculturing. The desiccated calli produced white friable calli which turned embryogenic and then produced somatic embryos in a medium containing 2 mg L–1 benzyl amino purine. The mature, club-shaped somatic embryos were germinated on a medium containing benzyl amino purine and a – naphthalene acetic acid in different concentrations. Type I callus of neither variety turned embryogenic but produced roots in all the cultures. Direct somatic embryogenesis was observed from the in planta aerial stem and leaf base explants with the use of thidiazuron alone or in combination with indole, 3-butyric acid. Histological studies revealed that the somatic embryos in ginger have a distinct single layered epidermis, scutellum, coleoptile, shoot apex and root apex.