Dissertation
Dissertation > Agricultural Sciences > Crop > Economic crops > Oil crops > Rapeseed ( Brassica )

Anayses of Genetic Diversity in Resynthesized Brasscia Napus L.

Author ZhangXingXing
Tutor NiuYingZe
School Sichuan Agricultural University
Course Crop Genetics and Breeding
Keywords Resynthesized Brassica napus L. Agronomic and economic characters SSR markers Genetic diversity Cluster analyses
CLC S565.4
Type Master's thesis
Year 2013
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Creation and broadening of the new germplasm resources of Brassica. napus L. are very important for promoting rapeseed breeding. In the past20years, a big group of new Brassica napus L. lines were resynthesized and developed in the Rapeseed Research Center of Sichuan Agricultural University, which exhibited a series of different excellent agronomic characters, including long siliques, big grains, big branch number, dwarf stature, yellow seed, white flower, resistance and tolerance to Sclerotinia sclerotiorum, and male sterility, etc. In the present study:96resynthesized Brasscia napus L.lines,and25lines of the normal Brasscia napus L. were selected, in a total of121lines, as the experimental materials. Observations were made for the main agronomic and economic characters, together with the differences in SSR markers in these lines in order to reveal the genetic diversity in the resynthesized Brasscia napus L. lines and the general lines, and to identify the lines with superior important agronomic and economic characteristics for utilization in rapeseed breeding. The main results are the following,:1. Eight main agronomic and economic characters were observed, including plant height, the height of the first effective branch, the length of the main raceme, number of the effective primary branches, the fruit density of primary branches, length of the pod body, number of grain per pod,1000-seed weight.Analyses the variation scope of the main agronomic and economic characters, average and coefficient of variation. Compared with Brasscia napus L., plant height, the height of the first effective branch, the length of the main raceme, number of the effective primary branches and the fruit density of primary branches of resynthesized Brasscia napus L. is lesser about Variability, and length of the pod body, number of grain per pod and1000-seed weight of resynthesized Brasscia napus L. is bigger about Variability. The fruit density of primary branches and fruit density of primary branches of resynthesized Brasscia napus L. respectively is biggest and least abut Variability; The plant height and1000-seed weight of Brasscia napus L. respectivly is biggest and least abut Variability.We found some special lines in resynthesized Brasscia napus L.(high,short, low strain of the first branch, length of main inflorescence, long siliques, many grains, haevy grain weight). Compared with Brasscia napus L.,some agronomic and economic characters of resynthesized Brasscia napus L. is more excellent(the length of the main raceme, length of the pod body,1000-seed weight),but some agronomic and economic characters(number of the effective primary branches, the fruit density of primary branches) is contrary.2. Clustering analysis was made for the121lines with their main agronomic and economic characters.The results showed that genetic similarity coefficient among the121lines ranged between0.1112and0.9992,and average is0.3510.Clustering indicated that the121lines could be divided into two groups (A and B) at a threshold value of0.455.The respectively number in group A and group B:95resynthesized Brasscia napus L. lines and7Brasscia napus L.lines,l resynthesized Brasscia napus L. lines and18Brasscia napus L.lines.Clustering indicated that the121lines could be divided into seven sub-groups (Ⅰ、 Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ) at a threshold value of0.305. The respectively number of sub-groups is five and two in group A and group B.All sub-groups are mixture,and the genetic variation is rich internal of sub-groups,and the genetic relationship between lines from different sources is more complex.3. From a total of600pairs of SSR primers,117pairs of polymorphic primers were identified, showing a total of417bands amplified, in which315bands were polymorphic. The Ratio of polymorphic primers and polymorphiic bands were19.5%and77.5%, respectively. Each pair of primers produced2.43bands on average, and the PIC range of each marker loci is between0.13and0.93,and average is0.70.Cluster analysis121lines by bands.The results showed that genetic similarity coefficient among the121lines ranged between0.44and0.86,and average is0.3510.Clustering indicated that the121lines could be divided into two groups (A and B) at a threshold value of0.59,resynthesized Brassica napus lines and Brassica napus are divided two groups(group A and B).Clustering indicated that the Brassica napus lines could be divided into three sub-groups (A1,A2and A3) at a threshold value of0.71,The numbers of included lines were5in B1,42in B2,8in B3,5in B4,11in B5,16in B6,3in B7,3in B8,3in B9.4. Clustering analyses of the121lines indicated that they could be divided into two main groups, containing seven sub-groups, based on their main agronomic and economic characters. The pedigree originations of the lines within each of the sub-groups were complex. With the SSR markers, the121lines could be divided into two main groups with ten sub-groups,,The resynthesized Brassica napus lines can be completely separated from the Brassica napus lines, the lines of each genealogical is complex within the resynthesized Brassica napus lines, but Brassica napus lines can be distinguished by period and geographic of breeding. Comparing the clustering results with main agronomic and economic characters and SSR markers, the similarity coefficient was0.3944, and t-test is Very significant, Description the clustering figure of main agronomic and economic characters and SSR markers is extremely consistency.It was revealed that the genetic diversity of the resynthesized Brassica napus lines was rich by SSR markers and the main agronomic and economic characters, and they are significantly variable in comparisons to the general Brassica napus lines.. Therefore, these resynthesized Brassica napus lines could be of potencial important uses in rapeseed breeding.

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