Somatic embryogenesis and plantlet regeneration from cultured shoots and cotyledons of seedlings from stored seeds of black and white sprees (Picea Mariana and Picea glauca)

Abstract

Embryogenic callus was induced from cultured explants of 12- to 30-day seedlings germinated from 10- and 4-year stored seeds of black and white spruce, respectively. Plantlets were regenerated from a 12-day black spruce seedling derived embryogenic callus. This is the oldest conifer seedling material shown to give rise to embryogenic callus, and the first demonstration in spruce that seedling-derived embryogenic calli are competent of plantlet regeneration. The effect of a cytokinin pretreatment on embryogenic callus induction from 12-day black spruce seedling shoot explants was investigated. Although an induction frequency of 18% occurred after 2 weeks preculture of shoot explants on medium containing 4.5 μM benzyladenine, the cytokinin pretreatment was not significantly superior to controls given no pretreatment (12%). Age of explant influenced embryogenic induction frequencies from black and white spruce. Explants from 21-day black spruce seedlings produced embryogenic calli at a frequency of 5%. In comparison, shoot explants from 12- and 30-day white spruce seedlings given no benzyladenine pretreatment displayed induction frequencies of 38 and 18%, respectively.