Stability and Inheritance of the Linum Insertion Sequence (LIS-1) in Transgenic Plants

The Linum Insertion Sequence (LIS-1) is an element that appears as a site-specific insertion event in flax responsive lines in response to certain growth conditions, and can be transmitted to subsequent generations. The origin of LIS-1 in the flax genome is uncertain. One theory is that LIS-1 is assembled from small sequences found scattered throughout the genome, and that, under stressful growth conditions, induction occurs and these sequences are rearranged and joined together to form LIS-1. It is unknown whether other plants have the same ability as flax to mobilize or rearrange LIS-1. The focus of this research is to develop transgenic plants containing LIS-1 in their genome, and to follow LIS-1 stability and inheritance in subsequent generations.

Agrobacterium-mediated transformation via floral dipping was used to generate transgenic plants (seven different Arabidopsis thaliana ecotypes and the fiber flax responsive line, “Stormont Cirrus”). The PCR results of the T1 and T2 transgenic Arabidopsis ecotypes confirm their ability to mobilize and rearrange the intact LIS-1 fragment, and these rearrangements seem to be genotype dependent. The results of the T1 transgenic flax show that LIS-1 is not stable in a responsive line as it disappears from the genome while the T1 plants are growing under non-inducing conditions, indicating that inducing conditions are required for LIS-1 to be maintained. These results demonstrate that Arabidopsis and flax have mechanisms for destabilizing an intact LIS-1 element.