Functional transient genetic transformation of Arabidopsis leaves by biolistic bombardment

Transient gene expression is an indispensable tool for studying functions of gene products. In the case of plants, transient introduction of genes by Agrobacterium infiltration is a method of choice for many species. However, this technique does not work efficiently in Arabidopsis leaf tissue, the most widely used model system for basic plant biology research. Here we present an optimized protocol for biolistic delivery of plasmid DNA into the epidermis of Arabidopsis leaves, which can be easily performed using the Bio-Rad Helios gene gun system. This protocol yields efficient and reproducible transient expression of diverse genes and is exemplified here for use in a functional assay of a transcription repressor and for the subcellular localization and cell-to-cell movement of plant viral movement protein. This protocol is suitable for studies of biological function and subcellular localization of the gene product of interest directly in planta by utilizing different types of activity-based assays. Using this procedure, the data are obtained after 2-4 d of work.