Seasonal changes in the transient expression of a 35S CaMV-GUS gene construct introduced into Scots pine buds.

Seasonal changes in the transient expression of Beta-glucuronidase gene (GUS) driven by a constitutive 35S CaMV-promoter in Scots pine (Pinus sylvestris L.) buds were studied by the microprojectile DNA-delivery method. Buds were collected from 5-, 15- and 50-year-old trees. In buds from all age groups the amount of transient expression was dependent on the season; the highest values were found in March, and values were lowest both at the beginning and at the end of the growing season. Pretreatment with growth regulators increased both the amount of transient GUS expression and arginine decarboxylase (ADC) activity in buds indicating an increase in metabolic activity. These results confirm that the genetic transformation technique can be used to study seasonally dependent regulation in mature Scots pine tissues.