Histological Examination of Callogenesis in Bisected Protocorm Culture of Pigeon Orchid (Dendrobium crumenatum Swartz)

Abstract

Callogenesis is a prerequisite step for the initiation of callus-mediated plant regeneration. Three-month-old protocorms of Dendrobium crumenatum Swartz (pigeon orchid) were bisected transversely and cultured on modified Vacin and Went (VW) solid medium containing 20 g L-1 sucrose, 2 g L-1 Phytagel added with various concentrations of 1-naphthaleneacetic acid (NAA) (0, 0.1, 0.5 mg L-1) and 6-benzyladenine (BA) (0, 1, 2 mg L-1). The highest percentage of callus formation was obtained from the explant cultured on a modified VW supplemented with 0.5 mg L-1 NAA and 1 mg L-1 BA. The callus originated from the subepidermal layer of the bisected protocorm and subsequently formed nodular structure after culture for 8 weeks. The callus mass contained small isodiametric cells with prominent nuclei and nucleoli within dense cytoplasm.

Keywords

• Bisected protocorm
• Dendrobium crumenatum
• nodular callus
• subepidermal layer