【作者】 陈小红；

【导师】 凡星；

【作者基本信息】 四川农业大学 ， 遗传学， 2015， 硕士

【摘要】 小麦族(Triticeae Dumortier)是禾本科(Poaceae)植物中最重要的一个类群之一,大约有500个种,不仅包括重要的粮食作物如小麦(Triticum aestivum L.)、黑麦(Secale cereal L.)和大麦(Hordeum vulgare L.),还包括许多具有经济价值的牧草,如：冰草(Agropyron cristatum (L.) Gaerton)、仲彬草属(Kengyilia Yen et J.L Yang)等。不仅包括一年生物种,还包括许多多年生物种。因此,研究小麦族的进化历史,可以为麦类作物的改良和牧草品质的提升提供遗传资源。小麦族植物包括许多二倍体植物和多倍体植物,其中70-75%的多倍体都是由不同的二倍体通过各种天然杂交组合的方式形成。目前得到广泛认可的分类方式是分类学家通过基因组的分类系统进行划分,现今得到认可的二倍体属主要有澳冰草属(Australopyrum)、冰草属(Agropyron)、簇毛麦属(Dasypyrum)、异形花属(Heteranthelium)、大麦属(Hordeum)、新麦草属(Psathyrostachys)、拟鹅观草属(Pseudoroegneria)等,多倍体属有仲彬草属(Kengyilia)、杜威草属(Douglasdeweya)、赖草属(Leymus)等。其中,冰草属(Agropyron)、仲彬草属(Kengyilia)、杜威草属(Douglasdeweya)都是含有P基因组的同源或异源多倍体物种。本研究对含P基因组的12个仲彬草属物种(14份材料)、2个冰草属物种(70份材料)、1个杜威草属物种(3份材料)及10个二倍体属物种(10份材料)186条CHS基因序列分析,构建系统发育树,探讨了CHS在P基因组物种中的系统发育和进化式样,研究主要结果及结论如下：1.结合系统发育、多态性、遗传距离及遗传分化系数进行分析,结果表明中亚、青藏高原、东亚和欧洲冰草四个居群间存在明显的遗传分化,中亚可能是冰草的多样性分布中心；2.冰草各居群dn/ds数据表明青藏高原冰草居群经历种群历史扩张保留较多的祖先遗传印记,有助于CHS为了更好的适应青藏高原的高海拔、高紫外照射等环境作出应答反应；3.中亚居群和青藏高原居群的仲彬草分别与当地的冰草属物种聚在一起,表明仲彬草属物种青藏高原和中亚种群可能是两个独立的起源,且CHS基因在这两个种群中存在不同进化潜能：青藏高原的仲彬草属物种受多倍化遗传瓶颈效应的影响,而中亚的仲彬草属物种可能通过重复杂交获得更多的冰草遗传物质；4.系统发育树的聚类结果表明,杜威草属物种和仲彬草属物种亲缘关系较近,D. deweyi的P基因组供体可能起源于中亚地区的Ag.cristatum；更多还原

【Abstract】 The tribe Triticeae, including about 500 species, is one of the most important group in Poaceae. It not only contains some of the world’s most important cereal, such as wheat (Triticum aestivum L.)、rye (Secale cereal L.) and barley (Hordeum vulgare L.), but also includes a significant number of important forage grasses. It also contains annual species and perennial species. Therefore, studying the evolution history of the Triticeae, would point to wild taxa that may serve as sources of novel gene pool.Triticeae consists of numerous diploids and polyploids, and polyploidy leads to the lineages of at least 70% of the species within Triticeae are polyploids. According to the system of genome classifications, the main diploid genera includes Australopyrum, Agropyron, Dasypyrum, Heteranthelium, Hordeum, Psathyrostachys, Pseudoroegneria and so on, while the polyploidy genera includes Kengyilia, Douglasdeweya, Leymus. Agropyron, Kengyilia and the Douglasdeweya are the diploid or polyploids, which contains P genome. To investigate the evolutionary dynamics of the CHS gene in species (Agropyron, Kengyilia and the Douglasdeweya) contains the P genome, the sequences from CHS gene of 12 species in Kengyilia (StYP), two species in Agropyron (P), one species in Douglasdeweya and 8 diploid (Australopyrum, Dasypyrum, Heteranthelium, Hordeum, Pasthyrostachys, Pseudoroegneria, Lophopyrum and Agropyron) species were analysised. Sequences diversity patterns and genealogical analysis suggested that:1. To analysis the Neighbor-Joining tree, polymorphism and genetic distances and Fst datas of the Agropyron from the four groups, it shows genetic differentiation obviously exists between the four populations, and Central Asia may be the diversity distribution center of Agropyron species.2. The dn/ds data shows that Agropyron from the Qinghai-Tibet Plateau group retains population expansion history of ancestral genetic imprinting, helps to CHS to response to the environmental factor, such as high UV irradiation, high altitude.3. In the Neighbor-Joining tree, the Kengyilia species of central Asia and the Qinghai-Tibet Plateau groups were clustered with the local Agropyron, It indicates that the geographic genetic differentiation may happened between the Qinghai-Tibet plateau and the Central Asia area of Kengyilia. they maybe origined independently in the two groups. CHS gene in the Kengyilia from the central Asia and the Qinghai-Tibet plateau have different evolutionary potential, the Kengyilia species from qinghai-tibet plateau affected by polyploidization genetic bottlenecks, and the Kengyilia species from central Asia may get more genetic materials of Agropyron species by repeated Hybridization events, and increased the genetic diversity of the Kengyilia species from the central Asia.4. To analysis the phylogenetic ralationships among the three genus, Agropyron, the results suggests that the relationships between Kengyilia and Douglasdeweya is closely, and Ag. cristatum from central Asia may donated the P genome to D. deweyi.更多还原