Agrobacterium-mediated expression of necrotic Cercospora beticola proteins.
The most economically important disease of sugar beet is Cercospora leaf spot (CLS) caused by the hemibiotrophic fungal pathogen Cercospora beticola. The pathogen causes foliar damage via necrotic lesions that, if left unmanaged, can significantly reduce crops yields. The lesions are caused by a plethora of effectors molecules, some of which have been previously characterized. The process of characterizing effector proteins can be tedious and involve difficult extraction and protein purification processes. In order to streamline the process of identifying putative effectors and their functions, transient gene expression methodologies can be employed. One such technique relies on the natural ability of Agrobacterium tumefaciens to transfer DNA into plants that will be subsequently integrated into their genomes. This ability has been coopted by researchers to express genes of interest in plant cells. Here, we developed lines of A. tumefaciens that express candidate C. beticola effector genes in the model plant Nicotiana benthamiana. When plants express a necrosis-inducing protein, cell death will occur in the plant tissue at the zone of infiltration. Consequently, this strategy allows for a high throughput means to screen C. beticola candidate effector proteins for the ability to induce necrosis. This strategy and the identification of C. beticola necrosis-inducing effector genes will be discussed.