Genetics ：柳枝稷遗传图谱绘制完成

2010/09/22 06:04:12

美国农业研究局（ARS）的科研人员近日发明了一种新的方法来破译本土草原上被广泛研究的一种草——柳枝稷（Switchgrass）的遗传特性。ARS位于加利福尼亚西部研究中心的克里斯蒂安.托比亚斯（Christian Tobias）及其同事在《遗传学》（Genetics）上发表的柳枝稷遗传图谱，有望加快寻找能够提高柳枝稷作为生物能源可靠来源的基因。

柳枝稷目前主要作为家畜的牧草，并可以用来修复贫瘠的土壤。但是近年来，由于它可以通过燃烧发电并且可以转变成乙醇，逐渐引起科研人员的兴趣。

为了绘制柳枝稷遗传图谱，研究人员采用了全同胞图谱绘制法（full-sib mapping），即以柳枝稷推广品种Kanlow为母本，ARS培育的品种Alamo为父本进行杂交，得到了238棵F1代；进一步从F1群体中提取 DNA并利用1000多个遗传标记完成了图谱的绘制。此图谱将柳枝稷的基因组分成了18个不同的组，每组的基因位于同一条DNA链上。

弄清柳枝稷的遗传结构能够带来巨大的好处。为使柳枝稷作为一种生物燃料进一步推广，科学家正在探索提高其产量并使其细胞壁更容易破裂的方法，这是从纤维质生产乙醇必要的一步。

柳枝稷的遗传图谱有助于发现与细胞壁组成、作物产量和其他有用特性相关的基因。科学家通过比较柳枝稷和水稻、高粱及其他植物的遗传图谱，可以更好地理解基因组，找到和植物中特殊品质相关的基因。

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Genetics doi:10.1534/genetics.110.113910

Complete Switchgrass Genetic Maps Reveal Subgenome Collinearity, Preferential Pairing and Multilocus Interactions

Miki Okada, Christina Lanzatella, Malay C. Saha, Joe Bouton, Rongling Wu and Christian M. Tobias

Polyploidy is an important aspect of the evolution of flowering plants. The potential of gene copies to diverge and evolve new functions is influenced by meiotic behavior of chromosomes leading to segregation as a single locus or duplicated loci. Switchgrass (Panicum virgatum) linkage maps were constructed using a full-sib population of 238 plants and SSR and STS markers to access the degree of preferential pairing and the structure of the tetraploid genome and as a step toward identification of loci underlying biomass feedstock quality and yield. The male and female framework map lengths were 1645 and 1376 cM with 97% of the genome estimated to be within 10 cM of a mapped marker in both maps. Each map coalesced into 18 linkage groups arranged into nine homeologous pairs. Comparative analysis of each homology group to the diploid sorghum genome identified clear syntenic relationships and collinear tracts. The number of markers with PCR amplicons that mapped across subgenomes was significantly fewer than expected, suggesting substantial subgenome divergence, while both the ratio of coupling to repulsion phase linkages and pattern of marker segregation indicated complete or near complete disomic inheritance. The proportion of transmission ratio distorted markers was relatively low, but the male map was more extensively affected by distorted transmission ratios and multilocus interactions, associated with spurious linkages.