Transposon tagging in heterologous plant systems offers a powerful tool for isolating genes for which no gene product is known, but for which a mutant phenotype can be observed. The experiments focus on existing populations of Ds-containing plants in the barley variety Golden Promise, an old malting variety, and additional populations to be developed in both Golden Promise and Oregon Wolfe Barley, a variety into which have been introgressed a combination of observable dominant and recessive mutations. Plant populations with randomly dispersed, transposed elements can be used directly to find easily screened mutations. A more powerful approach to tagging is to identify lines containing Ds insertions near genes of interest and exploit the propensity of Ds to undergo high-frequency, localized movement to achieve saturated mutagenesis of the regions of interest. Barley is an ideal cereal for this effort since it is closely related to and shares many physical and physiological characteristics with other cereals. It does not contain Ds homeologs, is a is true diploid, self-pollinating and easily grown in both greenhouse andfield environments. In addition, a vast pool of mapping data exists that is publicly available. Recent advances underpinning the proposed research include: a) efficient transposition of Ds to linked and unlinked sites in barley and its successful use in gene tagging; b) the availability of a fine structure genomic map of barley based on data from several public research consortia, including the North American Barley Mapping Project; c) the existence of many observable, dominant and recessive phenotypes in the Oregon Wolfe Barley (OWB) genetic stocks; and d) the availability of efficient transformation systems for a wide range of germplasm of barley. Taken together, these factors make possible the development of barley populations containing mapped Ds insertions. These elements, especially when mapped, will be valuable tools for performing functional genomics and gene isolation. These lines will increase understanding of basic cereal biology, instruct students about the modern tools available for genetic dissection and provide resources to improve the quality characteristics and field performance of cereals and potentially other crops.
