Regional Mutagenesis Utilizing Activator (Ac) in Maize

Boyce Thompson Institute Plant Research, Ithaca NY

Investigators

Abstract

Transposable element Activator (Ac) often moves to linked sites, thus limiting its use in non-targeted mutagenesis programs. To overcome this limitation, Ac will be distributed at approximately 10 cM intervals throughout the maize genome. Each of the approximately 200 non-transgenic 'anchor Ac (aAc) lines' in this near isogenic set will harbor a single active Ac element at a unique chromosomal locus. By utilizing an aAc line(s) that maps within 10 cM of any mapped gene or EST for directed tagging, these lines will provide an extremely powerful tool for gene isolation and functional analysis. In addition to facilitating the cloning of genes, the inbred nature of the population and low copy number of Ac elements in the genome will permit identification of subtle phenotypic changes in agronomically important traits such as plant height and flowering time. An equally important feature of this system is that multiple Ac-induced alleles can be generated from unstable Ac insertions to produce an allelic series. Thus, the generation of these aAc lines will provide an essential complement to the gene tagging programs currently being developed. This program will not only allow for the identification of novel mutant phenotypes, but will also provide a uniform genetic background for examining epistatic relationships and establishing genetic hierarchies. An important consideration in developing this system for general use, will be to determine the frequencies with which genes can be tagged relative to the position of the aAc. To address this issue, approximately 10,000 new transpositions will be selected from aAc's that have been distributed at roughly 10 cM intervals along chromosome 1S. Plants will be self-pollinated to generate segregating F2 populations that will be screened in sand benches and in the field for mutant phenotypes. Data from these studies will be used to develop a generalized strategy for directed and regional mutagenesis programs. An essential component of this program, is the development of the Emerson Summer Genetics Program to be established at the Boyce Thompson Institute and Cornell. This program will provide researchers from the US and abroad with the opportunity to utilize the Ac anchor lines while helping to generate the approximately 10,000 F1 and F2 families described above. Access to field sites is particularly important for researchers who are interested in initiating a maize genetics program and for those without access to field sites at their home institutions. To help bridge the gap between research and education, undergraduate students, high school teachers and a select group of high school seniors will be integrated into this program. Thus, teachers and students will spend up to 3 weeks in the field as a team with senior researchers from the US and abroad. The interactions and discussions that develop in the field and have long been part of the maize genetics tradition will help foster collaborations, increase public understanding of science and promote research in this agronomically important cereal. Deliverables: All maize seed stocks are propagated, genotyped and deposited as generated at: Maize Genetics Cooperation Stock Center c/o Dr. Marty Sachs (msachs@uiuc.edu) To view a list of Ac stocks currently available see: http://www.agron.missouri.edu/cgi-bin/cprop/stock_list.cgi#TK and for updates on the mapping progress see: http://bti.cornell.edu/Brutnell_lab2/Projects/Tagging/BMGG_pro_tagging.html