Transient transformation of sunflower leaf discs via an Agrobacterium-mediated method: applications for gene expression and silencing studies

The sunflower belongs to the Compositae family and is an economically important crop because of the quality of its oil. Unfortunately, molecular analyses are limited due to the lack of genomic information, mutant libraries and efficient and rapid transformation protocols. In a wide variety of species, Agrobacterium-mediated transient transformation is a useful tool that can provide valuable insight into many biological processes. However, this technology has not been routinely applied to the sunflower because of difficulties with infiltration. Here, we present an optimized protocol for Agrobacterium-mediated transient transformation of leaf discs. Using this procedure, we were able to quickly overexpress or silence a given gene, enabling us to study several biochemical processes and characterize sunflower regulatory sequences. One of the major advantages of this approach is that in only 1 work-week it is possible to acquire considerable molecular information while avoiding the use of controversial heterologous systems. Transforming heterologous species is frequently unacceptable, as the conservation of molecular events in many cases is not well documented.