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ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Publications at this Location » Publication #304715
Title: Behavior of a modified Dissociation element in barley: a tool for genetic studies and for breeding transgenic barley

Author
item BROWN, RYAN - General Mills, Inc
item SINGH, JASWINDER - McGill University - Canada
item SINGH, SURINDER - McGill University - Canada
item Dahleen, Lynn
item LEMAUX, PEGGY - University Of California
item STEIN, NILS - Leibniz Institute Of Plant Genetics And Crop Plant Research
item MASCHER, MARTIN - Leibniz Institute Of Plant Genetics And Crop Plant Research
item Bregitzer, Paul

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2015
Publication Date: 3/15/2015
Citation: Brown, R.H., Singh, J., Singh, S., Dahleen, L.S., Lemaux, P.S., Stein, N., Mascher, M., Bregitzer, P.P. 2015. Behavior of a synthetic Dissociation element in barley: A novel tool for genetic studies and for breeding transgenic barley. Molecular Breeding. 35:85.

Interpretive Summary: Transposons are mobile genetic sequences that are found in many plants and animals. Two closely-related transposons are known as Activator (Ac) and Dissociation (Ds). Both of these elements can move from one location to another, as a result of an enzyme (transposase) produced by Ac that acts recognizes and interacts with the ends of the Ac and Ds sequences. This system can function in other species, including barley. It can be used to move transgenes (i.e. genes from another organism) from an original insertion spot to another spot. All that is required for this to work is the attachment of the Ac/Ds ends to the transgene, and introduction of the transposase enzyme into the plant containing the transgene. This movement is advantageous for removing undesirable sequences at the original insertion site, such as selectable markers. To properly utilize this system, a detailed understanding of how it works in barley is needed. This study examined the frequency of transposition and the characteristics of the transposed loci. The results showed that transposition frequencies were high enough for practical use of the system. Also, most of the transposed transgenes moved to locations that likely will not affect native gene expression. These data will help advance breeding schemes for developing transgenic barley.

Technical Abstract: Maize-derived sequences from the transposable elements Activator (Ac) and Dissociation (Ds) have enabled studies of gene function via transposon tagging. The characteristics of synthetic, transgene-containing Ds elements constructed for some of these studies has demonstrated their ability to resolve complex loci, separate transgenes from marker genes and vector sequences, and to support high and heritable levels of transgene expression. To most efficiently design breeding schemes for developing transgenic populations via Ds-mediated transposition, detailed knowledge of the dynamics and characteristics of transposition in barley is necessary. Examination of a barley transposon tagging population (n = 4954) derived from crosses of lines containing Ds-bar insertions to lines expressing Ac transposase showed that the frequencies of transposition from eight original Ds-bar loci ranged from 5-41% among F2 individuals. Sequence analysis of Ds-bar terminal sequences and of flanking genomic sequences for 107 F2 and F3 individuals indicated precise integrations. Analysis of 173 flanking sequences derived from these populations and from previously-produced populations, primarily using sequence-based methods, enabled the mapping of 158 to a specific chromosome and136 to specific map locations. Of 156 DsT loci that could be located to specific contigs, most were located in gene-rich areas and approximately 40% were either in or near (within 1 kb) expressed sequences or predicted proteins. These data will enable the design of optimal breeding schemes for developing and using Ds-based systems for transposon tagging and for transgene delivery that are specific to barley.