Polyamine content and somatic embryogenesis in Papaver somniferum cells transformed with sam-1 gene

Papaver somniferum calluses transformed with the sam-1 gene from Arabidopsis thaliana, which encodes a SAM-synthetase, were subcultured over a 4-year period. The stability of the expression as well as the level of SAM synthetase activity were evaluated in 5 transgenic cell lines (STSI, STSII, STSIII, STSIV, STSV) and in the control. All transgenic cell lines exhibited a level of SAM-synthetase activity higher than that of the control. The enhancement of the enzyme activity has been confirmed by Northern blot analyses. The level of polyamines (putrescine, spermidine, spermine and 1,3-diaminopropane) was also evaluated in cell lines cultured either in Linsmaier and Skoog medium containing growth regulators (LS) or on a hormone free medium (LSHF). Cell lines cultured in LS medium showed a variable yield of the polyamine content. Putrescine was the major polyamine. After transfer to a hormone free medium, all of the cell lines, except STSIV, were able to form embryo-like structures. In this condition, the polyamine level decreases about 4-fold, spermidine being the most abundant.