Gene transfer by particle bombardment to Norway spruce and Scots pine pollen

The aim of the present work was to genetically transform Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) pollen in order to study the possibilities of obtaining transgenic progenies, The effects of different pollen origins and regulatory sequences on the beta-glucuronidase (GUS) expression in pollen were significant. The highest GUS expression in pine (55 +/- 7.7% of germinated pollen grains) was achieved with sunflower (Helianthus annuus) polyubiquitin promoter and in spruce (44 +/- 12% of germinated pollen grains), by using an abscisic acid inducible promoter of wheat (Triticum aestivum) EM gene. Our results indicate that high levels of transient foreign gene: expression can be achieved in pine and spruce pollen by using proper regulatory sequences for the target material and its physiological stage. Bombarded pollen was used for controlled pollinations in the greenhouse, after which 21% of the pine cones and 56% of the spruce cones developed normally.