In vitro culture of western red cedar (Thuja plicata). II. Induction of male strobili from vegetative shoot tips

Abstract

Vegetative shoot tips of mature western red cedar (Thuja plicata Donn) were cultured on defined nutrient media. In the presence of high concentrations of various gibberellins, microsporangiate strobili were induced from the vegetative tips during an 8-week period under continuous illumination. No strobili were induced by GA3 under short-day (SD; 8-h photoperiod) conditions or continuous darkness. The ontogenetic stages of strobilus induction and development in culture were similar to those reported for intact plants. Prolonged culture produced externally mature male strobili. However, histological examination of the sporogenous tissues revealed either abortion of the tissues or an apparent arrest in early meiosis. Wide concentration ranges of either IAA or NAA in the presence or absence of 1 × 10−4 M GA3 did not qualitatively modify the early development of male strobili or induce female strobili, although 1 × 10−4M IAA completely inhibited induction of the male strobili by GA3. Benzylaminopurine or kinetin suppressed the induction of male strobili by GA3, while Ethrel or abscisic acid at the concentrations tested had no apparent qualitative effects on microsporangiate strobili formation.