Polyamine Content in Relation to Embryo Growth and Dedifferentiation in Barley (Hordeum vulgareL.)

Putrescine, spermidine, and spermine content were analysed in zygotic embryos of barley (Hordeum vulgare L.). Changes in polyamine content were observed during zygotic embryo growth. In two cultivars, ‘Bomi’ and ‘Golden Promise’, the total polyamine content in the embryos was 2.6–2.9 nmol mg−1 fresh weight 10 d after anthesis, the highest content observed. It dropped to 1.3 nmol mg−1 fresh weight 14 d after anthesis. This drop was caused by decreases in all three polyamine concentrations. From 14 to 35 d after anthesis the putrescine content continued to decrease while the spermidine and spermine content increased, thus the total polyamine content remained constant until 35 d after anthesis. The mutant ‘Risø 1508’ showed a constant polyamine content around 1.3 nmol mg−1 fresh weight from 14 to 35 d after anthesis. The polyamine pattern was conserved in all three lines throughout the period of investigation showing a spermidine content higher than putrescine content which was, in turn, higher or equal to the spermine content. The polyamine content measured as nmol μg−1 protein decreased from 14 to 21 d post anthesis in all three lines, because the protein content (μg mg−1 fresh weight) increased during the period. In dedifferentiating zygotic embryos cultured in vitro the putrescine content (nmol mg−1 fresh weight) rose by a factor of nine and the spermidine content doubled within the first week of cultivation, whereas spermine content did not change. For embryoderived calli a repeated pattern of change in polyamine content was observed throughout the subculturing period.