IN-VITRO REGENERATION OF PACIFIC SILVER FIR (ABIES AMABILIS) PLANTLETS AND HISTOLOGICAL ANALYSIS OF SHOOT FORMATION

A protocol is described for the in vitro propagation of Abies amabilis (Dougl.) Forbes. Over 60% of the cotyledonary explants from 5-day-old cotyledons formed shoots when cultured for 7 days on Schenk and Hilde brandt's (SH) medium containing 10 mu M N-6-benzyladenine (BA) followe d by another 7 days on SH medium containing 10 mu M each of BA and zea tin. Shoot multiplication was unsuccessful. Seventeen percent rooting was obtained after pulsing for 4 h in 1 mM indole-3-butyric acid and p lanting pulsed shoots in 1/1 (v/v) perlite/vermiculite. Cell clusters (promeristemoids) of five to seven cells were observed on the cotyledo nary explants after 7 days of culture in the presence of cytokinin. Th ese cells developed further into meristematic domes and apical meriste ms. In the absence of cytokinin, stomata and resin canals reached matu rity, whereas cells within the cortex became vacuolated and developed into palisade and spongy mesophyll.