© 2005 Heron Publishing—Victoria, Canada
Somatic embryogenesis from vegetative shoot apices of mature trees of Pinus patula
Ravindra B. Malabadi (1) and Johannes Van Staden (1, 2)
1. Research Centre for Plant Growth and Development, School of Botany and Zoology, University of KwaZulu-Natal Pietermaritzburg,
Private Bag X01, Scottsville 3209, South Africa / 2. Corresponding author (vanstadenj@ukzn.ac.za) / Received February 2, 2004; accepted May 23, 2004; published online November 1, 2004
Summary
Embryogenic cultures were initiated and established from apical shoots of mature trees of three genotypes of Pinus patula Scheide et Deppe. Factors affecting initiation, including cold pretreatment, basal medium composition, growth regulators
and gelling agent concentration, and the effect of partial desiccation on somatic embryo maturation were investigated. Cold
pretreatment of thick sections (0.5–1.0 mm) of apical shoots at 2 °C for 3 days on 0.3% activated charcoal induced white mucilaginous
embryogenic callus on initiation medium. Subculture of this embryogenic callus on maintenance medium resulted in the formation
of embryonal suspensor masses with proembryos. Partial desiccation (12–90 h) of embryogenic tissue at the proembryo stage
of development, prior to transfer to maturation medium containing 9 g l–1 Gellan gum, enhanced somatic embryo maturation and germinability. The frequency of maturation increased from 5.3 to 16.5%
after 12 h of desiccation and from 16.5 to 73.8% after 24 h of desiccation, but longer periods of desiccation were ineffective.
Keywords:
clonal propagation, cold pretreatment, desiccation, tissue culture.
