Exogenous putrescine affects endogenous polyamine levels and the development of Picea abies somatic embryos

Abstract

Embryogenic cultures of Norway spruce (Picea abies) were treated with exogenous putrescine (Put) applied via either proliferation or maturation media to determine how such treatment affected endogenous poly- amine levels, the histological structures of the embryogenic suspensor mass (ESM), and the yield of mature embryos. Treatment with exogenous Put at 10, 100, or 500 lM significantly increased the endogenous free and conjugated Put contents of the treated ESM in a concentration- dependent manner. All of the Put treatments also reduced endogenous spermidine (Spd) levels. In conjunction with the increased abundance of endogenous Put, this caused a pronounced decrease in the Spd/Put ratios of treated ESMs relative to untreated controls. Exogenous Put stimulated meristem cell division and enlargement. However, single embryos were not readily released from polyembryonic centers and the frequency of development of malformed embryos was high.