TRANSIENT EXPRESSION OF REPORTER GENES INTRODUCED IN TISSUES OF TWO ACACIA SPECIES USING A BIOLISTIC METHOD

The biolistic method was used to introduced DNA into cotyledons of Acacia mangium and A. mearnsii. The β-glucuronidase gene (gus) and the green fluorescent protein gene (gfp) were tested as reporter genes to study the effects of acceleration pressure and pre- and post-bombardment osmotic treatments. These consisted of incubating the explants in the presence of sucrose, mannitol, and sorbitol for several hours before or after bombardment with microprojectiles. High acceleration pressure slightly enhanced gus expression in both species tissues. Osmotic treatments significantly improved expression of both reporter genes introduced into A. mearnsii cotyledons. The best transient expression was observed in these tissues when they were treated with mannitol and sorbitol (0.3 or 0.4M each) for 3–4h before the bombardment and 3h afterwards. However, the same treatments did not affect the expression of the gus gene introduced in A. mangium explants.