Genetic Diversity Of Winter Rapeseed In2001-2011National Regional Trials

Genetic diversity is the base of ecosystem diversity and an important part of biodiversity. In recent years, new variety varities have increased sharply in China to speed up the process of the breeding of hybrid rapeseed, but the genetic diversity of most population is relatively low. Analyzing the genetic diversity of winter rapeseed cultivars of national regional trials could assist us to understand the genetic structure, evaluated the germplasm resources, protected the wild and rare species and bred some new varieties. The two winter rapeseed cultivars during2009-2011have been analyzed by40SSR primers (PIC average value is0.77),and the clustering was made by NTSYS-pc2.1; genetic distance calculated by PowerMarkerV3.25; population structure studied by Structure2.2.We also analyzed the genetic diversity during2005-2011,and obtain the following conclusions:1. Mapping the2009-2011tree graph clustering, all of them were divided into eight clusters. Each of A, B groups, in2009-2010regional test, were divided into A1、A2, B1、 B2two subtribes; A group of2010-2011regional test were divided into two subtribes. Some varieties were obtained from the same breeding unit or the same regions always were classified in one cluster. It was shown that the genetic relationship of varieties from similar place are very close.2. The genetic similarity coefficient of whole winter rapeseed cultivars present normal distribution, the most number of combination on the0.6-0.7interval, and followed by the0.7-0.8interval. Two results of genetic similarity coefficient did not exist in the combination showing the genetic similarity coefficient less than0.5. There are individual combination in which the genetic similarity coefficient was greater than0.9, but the total number of them less than0.05%. The results indicated that they have far relationship, abundant genetic diversity and extensive genetic background. But, we still need to pay attention to it is not enough for introducting of rare wild germplasm resources.3. We studied the genetic diversity of the materials in different regions, the variation of the average value in the range of0.68-0.76. The group number of northwest population genetic similarity coefficient which is less than0.6accounted for the total group number ratio of only1.14%, and it of the East China region accounted for the total group area ratio was6.61%; PCA result showed that two populations, the southwest and east of China region, is most overlap in center location of the three-dimensional clustering diagram. The populations of northwest and central of China separated with the main population clearly, and southwest of rapeseed varieties in a wider range of distribution; population structure of2009-2010year all varieties divided into eight clusters, derived from the same region of the varieties were divided into one group, between different area can be apparent apart. The most simple population structure was the northwest material groups structure, and the most complex population structure was the central China material groups structure. Regional population structure analysis showed that the genetic diversity of area materials is low, population structure is single, but the relationship of regional materials is far and have high genetic difference. This result indicated that it has huge space for genetic exchange of regional varieties and the same area population genetic diversity needs to be improved.4. The nearly six years genetic similarity coefficient statistical comparisons we obsen’ed that, the genetic similarity coefficient of maximum value change in the range of0.91-0.96, and minimum value fluctuation range is larger, the average genetic similarity coefficient keep in the vicinity of0.67.Comparing the genetic similarity coefficient of nearly six years regional test materials exhibited that the genetic diversity has small changing and maintaining the stable state,minimal genetic similarity coefficient rises year by year and the genetic similarity coefficient were relatively concentrated in the narrow range.Six years regional test materials were classed according to the different regions. The results showed that the genetic similarity coefficient average value of all group remained in the vicinity of0.7. There was larger amplitude of genetic similarity coefficient in different rcgionals in2007-2009. The two annual China rapeseed regional trials population genetic background is wider, the genetic basis is abundant and phylogenetic relationship is far.In other years, the genetic similarity coefficient distribution are concentrated in0.9-0.8,0.8-0.7,0.7-0.6section.The middle reaches of the Yangtze River area group genetic similarity coefficient greater than0.9combinations in2005-2010five years all has distributing, the lower reaches of the Yangtze River area group genetic similarity coefficient greater than0.9combinations in the2005-2008three years has distribution, the relationship of materials in the middle reaches of Yangtze River are more closely.