Expression ofgusin somatic embryo cultures of black spruce after microprojectile bombardment

Immature embryos (stage I) and cotyledonary somatic embryos (stage III) of black spruve [Picea mariana (Mill) B.S.P.] were bombarded with tungsten particles coated with a gene construct containing the fusion of gus::nptll. GUS (β-glucuronidase) activity was monitored histochemically with X-gluc giving a blue colour where transient gene expression was detected in the bombarded tissues. A high transient expression of gus was observed in stage I embryo cultures 2 d after bombardment (202 GUS foci per 300 g tissue)