Regional Mutagenesis Utilizing Activator (Ac) in Maize

转座元件激活子（Ac）经常移动到链接的位点，从而限制了其在非靶向诱变程序中的应用。为了克服这一限制，Ac将在整个玉米基因组中以大约10 cM的间隔分布。在这个接近等基因的集合中，大约200个非转基因“锚定Ac （aAc）系”中的每一个都在一个独特的染色体位点上含有一个单一的活性Ac元件。通过利用aAc线(s)在任何定位基因或EST的10厘米内进行定向标记，这些线将为基因分离和功能分析提供极其强大的工具。除了促进基因的克隆外，群体的近交性质和基因组中Ac元素的低拷贝数将允许鉴定农艺上重要性状（如植物高度和开花时间）的微妙表型变化。该系统的一个同样重要的特点是，多个交流诱导的等位基因可以从不稳定的交流插入中产生，从而产生一个等位基因系列。因此，这些aAc系的产生将为目前正在开发的基因标记程序提供必要的补充。该程序不仅允许鉴定新的突变表型，而且还将为检查上位关系和建立遗传等级提供统一的遗传背景。在开发这一系统以供普遍使用时，一个重要的考虑因素将是确定基因相对于aAc位置可以被标记的频率。为了解决这个问题，将从分布在1S染色体上大约10厘米间隔的aAc中选择大约10,000个新的转位。植物将通过自花授粉产生分离的F2群体，这些群体将在沙地和田间进行突变表型筛选。这些研究的数据将用于制定定向和区域诱变计划的通用策略。该计划的一个重要组成部分是在博伊斯汤普森研究所和康奈尔大学建立的爱默生夏季遗传学计划的发展。该项目将为来自美国和国外的研究人员提供利用Ac锚线的机会，同时帮助生成上述大约10,000个F1和F2家族。对于那些有兴趣启动玉米遗传学项目的研究人员和那些在本国机构无法进入实地站点的研究人员来说，进入实地站点尤为重要。为了帮助弥合研究和教育之间的差距，本科生、高中教师和一组精选的高中毕业生将被纳入这个项目。因此，教师和学生将与来自美国和国外的高级研究人员组成一个团队，在实地度过长达3周的时间。在该领域开展的互动和讨论长期以来一直是玉米遗传学传统的一部分，将有助于促进合作，增加公众对科学的理解，并促进对这种具有重要农艺意义的谷物的研究。可交付成果：所有玉米种子库存都是在玉米遗传合作库存中心/ Marty Sachs博士（msachs@uiuc.edu）进行繁殖、基因分型和储存的。查看目前可用的Ac库存清单，请参阅：http://www.agron.missouri.edu/cgi-bin/cprop/stock_list.cgi#TKand，有关绘制进度的最新信息，请参阅：http://bti.cornell.edu/Brutnell_lab2/Projects/Tagging/BMGG_pro_tagging.html

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 Centerc/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#TKand for updates on the mapping progress see:http://bti.cornell.edu/Brutnell_lab2/Projects/Tagging/BMGG_pro_tagging.html