Plant regeneration from callus cultures of Morus indica L. derived from seedlings and mature plants

Abstract

A protocol for efficient plant regeneration from callus cultures derived from mature as well as seedling explants of Morus indica L. cultivar ‘S-13’ is described. Callus was successfully induced from internodal segments taken from a 5-year-old tree on Murashige and Skoog (MS) medium supplemented with a combination of 2.0 mg l −1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l −1 N 6-benzyladenine (BA). Hypocotyl segments derived from 15-day-old in vitro germinated seedlings callused on MS medium supplemented with 2.0 mg l −1 2,4-D alone. The internodal callus proliferated well on MS with 0.5 mg l −1 BA, 100 mg l −1 casein acid hydrolysate (CH) and 15% fresh coconut water (CW), whereas the hypocotyl callus required a combination of 2.0 mg l −1 1-naphthaleneacetic acid (NAA) and 0.2 mg l −1 BA for its proliferation. High frequency regeneration (83%) coupled with maximum number of shoot bud formation (about six buds per callus) was achieved from internodal callus cultured on MS supplemented with 0.5 mg l −1 BA. In hypocotyl-derived callus shoot bud regeneration occurred (65%, about four buds per callus) on MS with BA at the optimal level of 1.0 mg l −1. Histological observations confirmed de novo regeneration from callus derived from both types of explants. Internodal explants were more responsive than hypocotyl explants with respect to callus development and organogenesis. The regeneration potential was greatly influenced by the callus age. Rooting was induced in 98% of the regenerated shoots on half-strength MS supplemented with 1.0 mg l −1 indole-3-butyric acid (IBA). The rooted plantlets were hardened off and successfully established in the experimental field.