Poster: Emerging Technologies

Abs # 891: Site-specific gene integration in rice

Presenter:	Srivastava, Vibha , vibhas@uark.edu
Authors	Srivastava, Vibha  (A)   Ariza-Nieto, Magnolia  (A)   Wilson, Andrea  (A)
Affiliations:	(A): University of Arkansas

Traditional gene transfer methods result in the integration of foreign genes in random genomic location in a complex pattern, which causes variability in transgene expression between transgenic lines and gene silencing over successive generations. To stabilize transgene expression, a transgene should be precisely integrated in a pre-determined genomic location. For this purpose, site-specific gene integration methods have been developed which are based on a heterologous system such as Cre-lox. The objectives of the present project are (1) to develop an efficient method of site-specific transgene integration using particle bombardment, (2) to test the effectiveness of this method by assaying transgene expression in the site-specific integrant lines. We have generated several rice transgenic lines using the site-specific gene integration method. These plants fall in two categories; (1) single copy lines that contain a single copy of a transgene (gus) in a designated genomic location, (2) multi-copy lines that contain radom integrations in addition to the site-specific integration. Using particle bombardment and Cre-lox system, we obtained high efficiency of transgene integration at a designated genomic site. Further, the single copy integrant lines contain high transgene expression at more of less similar levels, while the multicopy lines display much lower level of expression. This data supports the notion that single copy integrant lines are stable, whereas multi-copy lines undergo gene silencing. Further, this data shows that it is possible to eliminate the variability of transgene expression between independent transgenic lines by using site-specific gene integration method.