Molecular phylogeny and origin of allopolyploid StH geonomic group in genus elymus

冰草属Escherichus与小麦、大麦和黑麦属于同一组。禾本科牧草适应了不同的气候和生境，是禾谷类和牧草育种的宝贵遗传资源，也是植物进化、遗传多样性、分类学和物种形成研究的优良类群。所有冰草都由至少两套不同的染色体组成，大多数物种具有StY和StH染色体组合。约有50个物种具有StH组合。St基因组来自Pseudoroegneria属的祖先物种，H来自野生大麦。关于这一群体的一个争论是，不同的StH物种是否是由一对亲本，一个假鹅观草属物种和一个野生大麦之间的古老杂交产生的，然后分化成许多物种（单一起源），或者不同的StH物种是由不同的亲本在不同的时间和地点之间的杂交产生的（多个起源）。以前的一些研究似乎支持多起源的假设，但没有提供有力的支持。我们将测试StH基因组组是否有多个起源。如果是这样的话，我们将看看我们是否可以确定哪些StH物种来自哪些假鹅观草（St）和野生大麦（H）物种使用DNA数据。在亚洲和北美洲有大量的Escherichus物种。欧亚和北美物种的遗传关系尚不清楚。我们将研究欧亚和北美物种之间的遗传关系。只有八种Escherichus物种原产于南美洲。它们与其他地区的Escherichus物种没有任何明显的联系。最有可能的联系是北美或新西兰。我们将研究这种联系是否存在。 这项研究的结果将提供重要的新知识的遗传关系的Escherichus。利用分子生物学方法了解披碱草属物种在地理区域内和地理区域之间的遗传关系，对于有效保护和利用该属遗传资源具有重要价值和意义。

Wheatgrass genus Elymus is within the same group as wheat, barley and rye. Grasses within the genus Elymus have adapted to various climates and habitats, making them valuable genetic resources for cereal and forage breeding as well as an excellent group for research in evolution, genetic diversity, taxonomy, and speciation in plants. All wheatgrasses are made up of at least two different sets of chromosomes with most species having StY and StH chromosome combination. There are about 50 species with StH combination. The St genome comes from ancestor species in genus Pseudoroegneria and H from wild barley. One debate on this group has been whether different StH species arose by an ancient cross between the one pair of parents, a Pseudoroegneria species and a wild barley and then differentiated into a number of species (single origin), or different StH species arose by crosses between different pairs of the parents at different times and places (multiple origins). Some previous studies seem to favor the hypothesis of a multiple origin, but did not provide strong support. We will test whether the StH genome group has multiple origins. If so, we will look at whether we can identify which StH species comes from which Pseudoroegneria (St) and wild barley (H) species using DNA data. Elymus species abundantly occur in Asia and North America. The genetic relationship of Eurasian and North American species is not clear. We shall examine the genetic relationships between Eurasian and North American species. Only eight Elymus species are native to South America. They do not have any obvious connections to Elymus species in other areas. The most probable connection would be with North America or New Zealand. We will examine whether such connections exist.      The outcome of this study will provide significant new knowledge on the genetic relationships of Elymus. The understanding of genetic relationships of Elymus species within and between geographic regions using molecular approaches is of great value and importance for the effective conservation and utilization of the genetic resources in the genus.