Gene traps as a tool for identification of plant genes involved in viral infection response

Transposable elements are used as insertional mutagenesis tools in plants, for example, the transposons of maize Ac (Activator) and Ds (Dissociation). These elements were modified to facilitate transposition in Arabidopsis thaliana with which gene tagging and cloning became possible. This tool is used mainly in biology of plant development, generating specific markers for tissues and cells. Its potential is broadening in studies of biotic stress caused by infection with phytopathogens such as geminivirus. The objective of this study was to use gene traps as a method to identify genes that respond to the infection of the geminivirus Cabbage leaf curl virus, CaLCuV, in A. thaliana plants. To carry out the study, 273 Mexican Gene Trap (MGT) and 233 Mexican Enhacer Trap (MET) transposant lines were used. Seedlings were bombarded with an infectious CaLCuV clone and then stained histochemically to detect expression of the reporter gene UidA (GUS) 1, 3, 5 and 7 d post infection (dpi). One of the genes identified was PGM, which codes for phosphoglycerate/biphosphoglycerate mutase and has an early tissue-specific response to the infection of A. thaliana by CaLCuV. To evaluate the function of the PGM gene during infection, an over-expressing line was generated. The results suggest that over-expression of PGM favors the rate of symptom appearance. However, the percentage of infection is very low. The use of gene traps enables massive, tissue-specific screening in real time during the infection, making it an alternative for initial identification of host genes involved in the response to geminivirus infection.