TRANSIENT BETA-GLUCURONIDASE EXPRESSION IN SCOTS PINE TISSUES DERIVED FROM MATURE TREES

Vegetative buds and bud-derived calli and suspension cells from 5- to 50-year-old Scots pines (Pinus sylvestris L.) were used as targets for biolistic transformation. The gene construct used in the experiments was 35S CaMV - beta-glucuronidase (GUS). The highest average level of transient GUS expression was found in suspension cells: 1229 +/- 359 (mean +/- SE) expressing cells per million. Transient expression was found in 35 of 44 (79%) tree genotypes studied. The expression level in buds and in calli was low: one or two spots per expressing bud. Growth-regulator pretreatment (BAP and 2,4-D) increased the number of GUS-expressing buds significantly. The high transient expression level in suspensions and the high percentage of GUS-expressing genotypes suggest that mature Scots pine tissues have potential for further transformation and genetic regulation studies.