Annals of Botany 90: 31-36, 2002
© 2002 Annals of Botany Company
Fluorescence in situ Hybridization Analysis of Alien Genes in Agrobacterium-mediated Cry1A(b)-transformed Rice
1 Key Lab of MOE for Plant Developmental Biology, Wuhan University, Wuhan 430072, P. R. China, 2 Institute of Biotechnology, Hainan University, Haikou 570228, P. R. China and 3 Department of Chemistry, Faculty of Science, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
* For correspondence. E-mail ycsong{at}whu.edu.cn
Received: 8 January 2002; Returned for revision: 5 March 2002; Accepted: 10 April 2002
The transgene in Agrobacterium-mediated Cry1A(b)-transgenic rice plants has been detected and its chromosomal location determined by fluorescence in situ hybridization (FISH). Eight of the nine transgenic lines tested showed hybridization signals. Signals were located on regions of the chromosome in which fraction length (FL) values varied from 26·2 (near the centromere) to 95·2 (distal regions). No signal was found on regions where the fraction length was less than 26·2, while six of the nine signals detected were located on regions with FL values of 75·3 or over. This demonstrates that Agrobacterium-mediated genes can integrate into multiple sites distributed in different parts of the chromosome, but that distal regions are the preferred sites and regions near the centromeres are colder for T-DNA integration. The donor DNA of the transformation was divided into two parts, labelled separately as probes for two-colour FISH. Results show that the transformed DNA sequences remained linked in the recipient genome. The relationship between integration position and transgene silencing, known as the ‘position effect’, is discussed.
Key words: Agrobacterium-mediated transformation, transgenic rice, fluorescence in situ hybridization, FISH, position effect, transgene silencing.