山药（Dioscorea spp.）种质资源遗传多样性分析及核心种质构建

Yam (Dioscorea spp.) is Dioscoreaceae (Dioscoreaceae) Dioscorea (Dioscorea) which is a annual or perennial twining herb with underground tubers for food.Yam is one kind of important vegetable crop and important Chinese traditional medicinal plant also with its strong adaptability, wide distributed and abundant local varieties. There is a rich germplasm in China. However, only few studies about yam genetic diversity in domestic has been reported and many yam germplasm is ignored.Yam production,germplasm study and breeding is effected by confuse varieties and not clear species classification system seriously.Further more, most of yam material is easy to be lost in long storage time,big spaces and easy to be effected by plant diseases and insects and storage condition also. So it is necessary for analysis genetic diversity and construction core collection of yam to avoid these problems. 60 yam (Dioscorea spp.) material have been collected from 4 main area of yam geographical distribution in China,including 57 Chinese yam(D.opposita Thunb.)，2 yam (D.alata L.) and 1 wild yam(D.Doryophora Hance)。Yam material will be investigated focus on morphologicl and agronomic characteristics and ISSR-PCR. Genetic diversity of all yam germplasm will be analyzed by ISSR molecular markers combined morphology and agronomy characteristics. Core collection will be constructed with least distance stepwise sampling (LDSS) and prior sampling respectively by ISSR and morphology cluster. And then the representative of the core collection will be investigated on the total loci amplified by selected ISSR primers including polymorphic loci and the average of Shannon information index (I),Nei's genetic diversity(H) and effective number of alleles(NE) by POPGENE 32 analysis respectively. The result of analysis by NTSYS-PC software will show coherence between the clustering result and source core germplasm collection.This core collection will provide an effective mechanism for the proper exploitation of yam germplasm resources for the genetic improvement of this crop.

山药(Dioscorea spp.)为薯蓣科（Dioscoreaceae）薯蓣属（Dioscorea）中一年生或多年生缠绕性草质藤本植物。山药适应性强，分布广，在我国形成了诸多地方品种，种质资源丰富。但各地山药品种同物异名或同名异物的现象比较突出，给山药的生产、系统分类、种质资源研究及育种造成很大困难。此外，保存山药块茎占用空间较大，易受虫害、气象等因素影响，每年因此而丢失不少种质资源。课题组认为研究山药遗传多样性和构建山药核心种质是解决上述问题的有效途径。课题组陆续从全国各地收集、整理山药种、品种60份，拟利用形态学聚类方法，主成分分析，ISSR 分子标记聚类法，分析山药种质资源的遗传多样性。同时利用最小遗传距离逐步取样法和聚类优先取样法分别筛选山药核心样品，并检测这些核心样品的代表性，以构建山药核心种质。为山药种质资源创新和遗传改良提供科学依据。

山药(Dioscorea spp.)为薯蓣科（Dioscoreaceae）薯蓣属（Dioscorea）中一年生或多年 生缠绕性草质藤本植物。山药适应性强，分布广，在我国形成了诸多地方品种，种质资源 丰富。但各地山药品种同物异名或同名异物的现象比较突出，给山药的生产、系统分类、 种质资源研究及育种造成很大困难。此外，保存山药块茎占用空间较大，易受虫害、气象 等因素影响，每年因此而丢失不少种质资源。课题组认为研究山药遗传多样性和构建山药 核心种质是解决上述问题的有效途径。课题组陆续从全国各地收集、整理薯蓣属植物80份，其中山药种、品种60 份。对其中60份山药种质资源分别采用形态法和ISSR分子标记法分别构建核心库。.形态法利用优先抽样法结合非加权类平均法，按照70%～10%的抽样比例构建六个核心子集XT70～XT10，对这六个核心子集在均值差异百分率(MD%)、方差差异百分率(VD%)、极差符合率(CR%)以及变异系数变化率(VR%)这四个性状变异比率进行了比较，发现在抽样比率为30%时所构建的核心子集XT30遗传多样性指数高，且不会失去某些特殊性状，因此其对原始群体代表性也最强，可以作为基于表型性状的核心种质。.ISSR分子标记法按照最小距离逐步抽样法，在70%～10%的抽样比例下构建六个核心子集，通过对这些核心子集遗传多样性的比较，发现随着抽样种质数目的减少，遗传多样性参数变化较小，各遗传多样性指数的多重比较结果表明，选取30%抽样比例构建的核心子集FZ30最能代表原始群体遗传多样性，可以作为基于ISSR分子标记的核心种质库。最终确定核心种质20份可以作为基于ISSR分子标记的核心种质库。其中包括河南温县铁棍山药（D.opposita），内蒙古毕克齐山药（D.opposita）、山西太谷太怀山药（D.opposita），山东嘉祥细毛山药（D.opposita），大和长芋山药（Dioscorea alata.）陕西华县山药（D.opposita），山西北洋山药（D.opposita），江西永丰山药（D.opposita），江西瑞昌山药（D.opposita），云南会泽山药（D.opposita）等。核心种质20份材料与原始群体的主坐标分析结果进一步证明了核心种质在空间上可以充分代表原始群体。这些材料是山药种质资源的主干种质，将在山药种质资源保护、利用、创新等方面发挥