Genetic Map-Based Analysis of Paleopolploidy in Homosporous Ferns

世界上的植物由同孢子植物和异孢子植物组成，同孢子植物以蕨类植物为代表，异孢子植物以种子植物为代表。 同孢子物种具有高的染色体数目，表明它们是染色体数目加倍（多倍性）随后基因/基因组沉默的重复循环的产物。 该项目将通过生成Ceratopteris richardii的39条染色体的高分辨率遗传图谱来解决古代多倍性的问题，Ceratopteris richardii是一种蕨类植物，用作同型孢子植物研究的模式生物。 将用大约1000个分子标记分析来自500个完全近交杂交植物（DHL）的DNA。 分析重复标记的染色体位置将有可能确定水蕨属物种是否是一个古老的多倍体。现在已知同孢植物与种子植物共享一个直接的共同祖先，种子植物包括所有农业食品植物。 该项目的遗传图谱将提供有关同孢子植物基因组结构的基本信息，这反过来又将提供有关产生今天所有植物基因组组织的进化过程的基本比较数据。 除了基因图谱，500株完全基因型的DHL植物将被克隆，并免费提供给生物学家用于未来的基因研究。

The world's plants consist of homosporous plants, best represented by ferns, and heterosporous plants, best represented by seed plants. Homosporous species have high chromosome numbers, suggesting that they are products of repeated cycles of doubling of chromosome numbers (polyploidy) followed by gene/genome silencing. This project will address the question of ancient polyploidy by generating high resolution genetic maps of the 39 chromosomes of Ceratopteris richardii, the fern species used as a model organism for studies of homosporous plants. DNAs from 500 completely inbred hybrid plants (DHLs) will be analyzed with approximately 1000 molecular markers. Analyses of the chromosomal locations of duplicate markers will make it possible to determine whether the Ceratopteris species is an ancient polyploid.Homosporous plants are now known to share an immediate common ancestor with seed plants, a group that includes all agricultural food plants. This project's genetic maps will provide fundamental information about genomic structure of homosporous plants, which in turn will provide basic comparative data bearing on evolutionary processes that produced the genomic organization of all of today's plants. In addition to the genetic maps, the 500 fully genotyped DHL plants will be cloned and made freely available to biologists for future genetic studies.