小麦族偃麦草属的系统地位及其物种分类研究

Elytrigia Desv. is one of the important perennial genera in the tribe Triticeae (Poaceae). It includes about 40 species in the world, and is distributed in the subtropical and warm temperate countries of both hemispheres. Species in Elytrigia are excelent fodder plants, and some species are used in wheat breeding program through distant hybridization as the genetic germplasm resources for disease and drought resistance, and salt tolerance. However, the definition of the genus and its precise taxonomic treatment are still under discussion. Therefore, in this program, we carried out the taxonomic status of Elytrigia and biosystematic study on its species through morphological characters, geographic distribution, intergeneric and interspecific hybridization, fertility, cytogenetic characterization, genomic in situ hybridization (GISH) and molecular systmatic studies. The objectives are: (1) to investigate taxonomic ststus of genus Elytrigia; (2) to study taxonomic ststus of genus Trichopyrum Love and the relationship between Trichopyrum and Elyrtigia; (3) to discuss the generic delimitation and the phylogenetic relationships among Elytrigia, Lophopyrum, Pseudoroegneria and the related genera Elymus and Roegneria; (4) to determine the genomic constitution of the species and the chromosome number variations among the intraspecific populations; (5) to analyze the fertility among the species and intraspecific populations; (6) to discuss the specific delimitation, the phylogenetic relationships among the species, and the taxonomic treatment of the intraspecific taxon; (7) to solve the problems about the specific taxonmic treatment, and revise the genus Elytrigia and genus Lophopyrum.

通过对世界范围内传统偃麦草属物种的形态特征和地理分布、属间和种间杂交及繁育特性、细胞学和细胞遗传学、基因组原位杂交（GISH）和分子系统学等研究结果进行分析，探讨：（1）偃麦草属的系统地位；（2）毛麦草属属的地位及其与偃麦草属的关系；（3）偃麦草属与冠麦草属、拟鹅观草属和披碱草属等近缘属的属间界限和亲缘关系；（4）物种染色体组组成和种内居群间染色体数目的倍性变异；（5）种间和种内居群间，特别染色体不同倍性变异居群间植物的繁殖特性；（6）物种界限、种间关系和种下等级的分类处理；（7）解决部分物种分类处理的疑难问题，系统整理偃麦草属和冠麦草属植物。为全面认识传统偃麦草属植物以及小麦族多年生多倍体属的起源和演化提供资料。

偃麦草属是小麦族中一个形态多样，变异极大的一个属，其属的系统地位、与近缘属的关系、物种的分类以及起源和演化，争议极大。本研究通过形态特征、属间和种间杂交、细胞遗传学、基因组原位杂交（GISH）和分子系统学等手段，研究了偃麦草属的系统地位，与近缘属的亲缘关系，物种分类以及起源和演化，取得如下重要研究进展和成绩：（1）偃麦草属模式种Elytrigia repens含有StStH染色体组，应组合到披碱草属作为Elymus repens处理，因此，偃麦草属是一个无效的属，澄清其生物学本质。（2）广义偃麦草属中，具St染色体组物种应划到拟鹅观草属，具StH染色体组物种放在狭义披碱草属，StE物种放在毛麦草属，EeEe或EbEb物种划到冠麦草属，而StEP的物种划分到沙滩麦属中，确立了冠麦草属、毛麦草属、沙滩麦属的系统地位，研究了与近缘属拟鹅观草属、披碱草属的系统关系。（3）澄清了部分物种的分类处理。模式种E. repens和E. lolioides染色体组为StStH，E. kosaninii为StH染色体组，应组合到披碱草属中；E. pungens为StStEP，E. pycnantha为StEP，应组合到沙滩麦属中；E. intermedia、E. geniculata subsp. pruinifera和subsp. scythica为StE或StEE，应组合到毛麦草属中；E. pontica染色体组成为EEEEE，应组合到冠麦草属中。（4）广义偃麦草属具Ee、Eb、St、H、P等5个基本染色体组，St来自拟鹅观草属，H来自大麦属，Ee来自长穗冠麦草，而Eb来自百萨冠麦草，P来源冰草属。结合前人和本研究结果，阐明了广义偃麦草属的染色体组起源和演化。（5）建立和完善资源圃和种子资源库，收集和保存偃麦草属34种168份及近缘属9属95种587份，标本42种214份。（6）在Mol Phylogenet Evol、Ann Bot、Bot J Linn Soc、Gene、BMC Plant Biol、J Syst Evol、Bioch Syst Ecol、Caryologia等发表SCI论文22篇，会议论文10余篇。出版专著1部。获国家发明授权专利1项。选育小麦和牧草新品种2个。获四川省科技进步二等奖1项。（7）招收博士后1人、博士7名、硕士12名，毕业博士3名、硕士7名。