Evaluation of Three Constitutive Citrus Promoters in Citrus Transgenic Plants

Transgenic technology can provides genetic solutions to major problems affecting citrus species. The success of gene transfer technologies depends on the selection of appropriate promoter that induces expression of transgene at desired levels. Among the promoters usually employed, there is the constitutive promoter CaMV35S isolated from the Cauliflower Mosaic Virus, which is the most widely used promoter in plant biotechnology. However, new approaches for plant transformation (intragenesis and cisgenesis) requires use of genetic material derived from the species itself or related species. Thus, it is necessary to increase the availability of constitutive promoters derived from citrus for genetic transformation. The aim of this study was to evaluate the functionality of three constitutive citrus promoters. Hence, the promoter region of the citrus genes GAPDH (glyceraldehyde-3-phosphate dehydrogenase), EF1-α (elongation factor 1-α) and CYP (cyclophilin) were isolated and inserted into a transformation vector fused to the reporter gene uidA (GUS). The promoter functionality was analyzed in transgenic lines of Citrus sinensis cv. Hamlin positive for PCR analysis. Histochemical staining of GUS activity showed GUS staining in the leaves and the roots of all transgenic plants with different promoter construct. The GUS expression was confirmed in transgenic plants containing each promoter construct by RT-qPCR analysis.

Support: FAPESP