Casa A M, Brouwer C, Nagel A, Wang L, Zhang Q, Kresovich S, Wessler S R
Departments of Botany and Genetics, The University of Georgia, Athens, GA 30602, USA.
Proc Natl Acad Sci U S A. 2000 Aug 29;97(18):10083-9. doi: 10.1073/pnas.97.18.10083.
Transposable elements are ubiquitous in plant genomes, where they frequently comprise the majority of genomic DNA. The maize genome, which is believed to be structurally representative of large plant genomes, contains single genes or small gene islands interspersed with much longer blocks of retrotransposons. Given this organization, it would be desirable to identify molecular markers preferentially located in genic regions. In this report, the features of a newly described family of miniature inverted repeat transposable elements (MITEs) (called Heartbreaker), including high copy number and polymorphism, stability, and preference for genic regions, have been exploited in the development of a class of molecular markers for maize. To this end, a modification of the AFLP procedure called transposon display was used to generate and display hundreds of genomic fragments anchored in Hbr elements. An average of 52 markers were amplified for each primer combination tested. In all, 213 polymorphic fragments were reliably scored and mapped in 100 recombinant inbred lines derived from a cross between the maize inbreds B73 x Mo17. In this mapping population, Hbr markers are distributed evenly across the 10 maize chromosomes. This procedure should be of general use in the development of markers for other MITE families in maize and in other plant and animal species where MITEs have been identified.
转座元件在植物基因组中普遍存在，在植物基因组中它们常常构成基因组DNA的大部分。玉米基因组被认为在结构上代表了大型植物基因组，它包含单个基因或小的基因岛，这些基因岛散布在更长的反转录转座子片段之间。鉴于这种基因组组织形式，鉴定优先位于基因区域的分子标记将是很有必要的。在本报告中，一个新描述的微型反向重复转座元件（MITEs）家族（称为“心碎者”）的特性，包括高拷贝数、多态性、稳定性以及对基因区域的偏好性，已被用于开发一类玉米分子标记。为此，一种称为转座子展示的AFLP程序改进方法被用于生成并展示数百个锚定在Hbr元件上的基因组片段。对所测试的每个引物组合平均扩增出52个标记。总共，213个多态性片段在来自玉米自交系B73×Mo17杂交的100个重组自交系中得到可靠评分并进行了定位。在这个定位群体中，Hbr标记均匀分布在10条玉米染色体上。该程序在开发玉米中其他MITE家族以及已鉴定出MITEs的其他植物和动物物种的标记时应具有普遍用途。
