Transient plant gene expression: a simple and reproducible method based on flowing particle gun.

Successful transient expression of beta-glucuronidase (Gus) and luciferase (Luc) in Nicotiana tabacum leaves was obtained after gene delivery by a simple and inexpensive particle gun. Takeuchi's biolistic process system was adapted to accelerate directly in a helium stream DNA-coated microprojectiles into intact plant leaf tissues. After bombardment of p70-omega-59Gus construction (duplication of the CaMV 35S enhancer), variability inherent to the bombardment procedure was observed in Gus activity measurements between replicate samples. We therefore included an internal standard (35S-Luc) in each bombardment, allowing an accurate, sensitive and reproducible comparison of the effective strength of different Gus-reporter constructs based on Gus/Luc ratio measurements.