Systematics and Molecular Evolution of Perennial Soybean Polyploid Complexes

[0089483]多伊尔和布朗康奈尔大学的杰夫·多伊尔与他在澳大利亚联邦科学与工业研究组织的同事托尼·布朗一起，继续进行他的高评价的研究，研究多年生大豆品种甘氨酸多倍体进化的基因标记和遗传后果，甘氨酸多年生大豆品种与栽培的一年生大豆有关。多倍体，或全染色体重复，在植物中很常见，在世界上的主要作物植物中尤其普遍。17种已命名的二倍体多年生大豆及其众多多倍体衍生物分布在大洋洲和东南太平洋岛屿，在CSIRO大豆种质资源收藏中有广泛的代表性。一个主要目标是利用基因组工具，在野生物种中探索从小麦和卷心菜多倍体研究中形成的基因沉默和核仁优势的想法，并将这种研究扩展到几个单拷贝或低拷贝核基因。使用物种复合体，其中亲本二倍体已被确定（亲本四倍体为六倍体和八倍体衍生物），并且“相同”多倍体的多个起源可以用核和叶绿体基因组的分子标记来记录。复制（同源）位点的命运研究将通过克隆PCR产物进行，但研究人员也在探索使用变性色谱方法筛选大量多倍体样本，以寻找新等位基因的存在（从长度或序列不同的等位基因退火分离的异双工，产生诊断性洗脱谱）。核组蛋白基因（H3-D）、核谷氨酰胺合成酶、cox2（从许多豆科植物的线粒体转位）和核糖体RNA基因的初步数据已经到手。通过与杜邦公司的朱莉·沃格尔（Julie Vogel）合作，获得杜邦公司的20万个大豆cDNA克隆，研究人员还计划筛选显示沉默的候选核基因（通过与二倍体和多倍体dna的差异杂交），并将重点放在那些在叶绿体或线粒体中起作用的基因上（因此，父系同源物被认为可能被沉默）。

0089483Doyle and BrownWith his CSIRO-Australia colleague Tony Brown, Jeff Doyle at Cornell University is continuing his highly rated studies on gene markers and genetic consequences of polyploid evolution in the perennial species of soybean, Glycine, related to the cultivated annual G. max. Polyploidy, or whole-chromosome duplication, is common in plants, and especially prevalent among the major crop plants of the world. The 17 named diploid perennial soybeans and their numerous polyploid derivatives are distributed in Australasia and the southeastern Pacific islands, and are extensively represented in the CSIRO soybean germplasm collection. One major goal is to explore in wild species, with genomic tools, ideas about gene silencing and nucleolar dominance formulated from studies on wheat and cabbage polyploids, and to extend such studies to several single- or low-copy nuclear genes, using species complexes where the parent diploids have been identified (and parent tetraploids for hexaploid and octoploid derivatives) and where multiple origins of the "same" polyploid can be documented with molecular markers from both nuclear and chloroplast genomes. Studies of the fate of duplicated (homoeologous) loci will be pursued through cloning of the PCR products, but the investigators are also exploring use of denaturing chromatographic methods to screen numerous polyploid samples for the presence of novel alleles (heteroduplexes from annealing of alleles that differ in length or sequence separate, producing diagnostic elution profiles). Preliminary data are in hand for a nuclear histone gene (H3-D), for nuclear glutamine synthetase, for cox2 (transposed from the mitochondrion in many legumes), and the ribosomal RNA genes. In collaboration with Julie Vogel at DuPont, with access to DuPont's 200,000 soybean cDNA clones, the investigators also plan to screen for candidate nuclear genes showing silencing (through differential hybridization with diploid and polyploid DNAs), and concentrate on those that function in the chloroplast or mitochondrion (and hence where the paternal homoeologue is thought likely to be silenced).