GENETIC TRANSFORMATION AND HYBRIDIZATION

Peroxidases constitute a large family of pro- teins found in all higher plants. Owing to the complexity of the peroxidase isoenzyme family it has been difficult to assess the precise function of individual peroxidase enzymes. In this work we have studied the effects of an endogenous peroxidase-like gene from Norway spruce (Picea abies (L.) Karst), spi 2, on the development and growth of Norway spruce somatic embryo plants. Em- bryogenic cells of Norway spruce transformed with spi 2 under control of the maize ubi-1 promoter showed up to 40 times higher total peroxidase activity than the control cells; regenerated plants overexpressing spi 2 showed an increased total peroxidase activity. Based on these results and the overall sequence similarity with cationic peroxi- dases we conclude that spi 2 encodes a peroxidase. Over- expression of spi 2 resulted in increased sensitivity to stress, leading to a reduction in epicotyl formation and in height growth compared with control plants. The plants overexpressing spi 2 also showed a deeper phlorogluci- nol staining but similar levels of Klason lignin.