The Correlativity Analysis Between Genetic Diversity And Dominant Characters Of Brassica Oleracea L. Var.capitata, The Purity Identification Of Hybrid Based On RAPD Markers

Heterosis is an ubiquitous phenomena in living nature, and the application of heterosis has become the important way to improve the output and quality of many crops. For a long time, breeders have been seeking a convenience and swift method to predict heterosis .Using morphological markers and abilities of parents combining to predict heterosis needs evaluating a large number of combinations in field, it woud not only costing a lot of time and labors, but also affect by environment factors. The prediction based on isozymes usually work well for its samll quantity. Because molecular markers can reflecting the difference at DNA array level, covering the whole genome, the quantity nearly limitless, and not influenced by environment and the time of samp collecting , its offer a new way to deeply study the heterosis of crops. Cabbage is one of the vegetable crops in which heterosis are most commonly applied, and to study the blood relation and genitic diversity will be especially important. Our country has already bred a large number of cabbage F₁ cultivars so far. It is rather difficult to distinguish these cultivars by traditional purity identification methods for the little different between thoes cultivars, and so it is essential to develop fingerprint of every variety throug. molecular markers. These fingerprints are also important to protection of the hybrid seeds, preventing damaging the rights of peasants and breeders by fake seeds.The author used RAPD marker to analyze the genetic diversity of sixty cabbage materials and the correlativity between the hereditary distance and the dominant characters and discussed the feasibility of molecular markers used in the heterosis prediction. In addition, the author set up the purity identification system of the cabbage of XiYuan NO.6 by primer S86.1 Analysis of dominat characters of 12 hybrid varietiesThe results of Investigation on 12 combination of cabbage showed : (1) the average values of over-parent heterosis and mid-parent heterosis were 13.65% and 23.49% respectivly in the characters of solidity of head. All the 12 cross combinations but 2 were superior to their parents. Results showed that solidity of head of major cross combinations were greater than those of parents. (2)the average values of over-parent heterosis and mid-parent heterosis were 35.81% and 66.7% in head weight, all average values were greater than those of parents,except NO1 cross combination.its over-paren heterosis is negative. The Results showed that the cabbage yields of major cross combinations were higher than those of their parents. (3) the average values of over-parent heterosis and mid-parent heterosis were all positive in central axis, which were 45.15% and 21.19% respectivly. The length of central axis of all cross combinations were longer than those of parents. (5)the average value of mid-parent heterosis was -16.5% in head index. They were negative except two cross combinations. The Results showed that the head indexes of major cross combinations were lower than that of parents. F1 tend to be oblater . (6)the average value of mid-parent heterosis was -1.57% in longitudinal diameter of the head, they were negative except two cross combinations. The Results showed that the longitudinal diameters of major cross combinations were shorter than average length of parents.(7)the mid-parent heterosis of transverse diameter were positive and the average value is 20.17%.The Results showed that the transverse diameters of major cross combinations were longer than those of parents with shorter transverse diameter. Combining head index, longitudinal diameter and transverse diameters of cross combinations to analyze, the author found that, with the longitudinal diameter of cross combinations shorten, transverse diameters got longer and the head index got lower, that was the majority of combinations were oblater.2. Analysis of genetic diversity of 60 varieties150 arbitrary primers were used in RAPD of 60 cabbage materials, 95 primers had polymorphism, which account for 63%. 534 polymorphic locations were obtained. We used these polymorphic locations to caculate genetic distance (GD) based on molecular markers of 60 cabbage materials, and then to make the cluster analysis.Combining cluster results of 60 cabbage materials and the corresponding field properties to analyze, the author found the variation range of hereditary distance of sixty materials at 0.12869～0.45809, relatively little. At GD 0.12, 60 materials were clustered into different types each other.At GD 0.38, all materials were only clustered into one type. At GD 0.239, materials were clustered into 15 types, 17 materials come from overseas were clustered into 10 types, but 43 materials come from our country were only clustered into 10 types, indicating that the genetic diversity of materials come from our country is relatively lower, compared with materials come from overseas. 3 The correlation analysis of genetic distance (GD) and dominant character of 12 hybrid varietiesAt GD range of 0.1989～0.25689, the results shows that, (1) there were significantly negative correlation between over-parent heterosis of the solidity of head and genetic distance. The correlation coefficient was -0.709, it indicated that with the increase of genetic distance, the solidity of head decreased . (2) there were significantly positive correlation between over-parent heterosis or mid-parent heterosis of central axis and genetic distance. The correlation coefficient was 0.7719,0.7291 respectively. It indicated that with the increase of genetic distance, the length of central axis increased. (3) there were significantly positive correlation between mid-parent heterosis of longitudinal diameter of the head and genetic distance. The correlation coefficient was 0.8140. It indicated that with the increase of genetic distance, the longitudinal diameter of the head increased. So at range of 0.1989～0.25689, It is instructive to select parents of advantage character.To analyze the genetic distance and correlated character of parents (hybrid varieties, Xiyuan No.4, Xiyuan No.6, Xiyuan No.8), we found that not all characters were superior to that of parents. It indicated that breeding selection depends on breeding objecti4 Establishment of seed purity identification system of cabbage "Xiyuan No.6"4.1 Obtaining the fingerprint of seed purity identificationThe parents of "Xiyuan No.6" were analyzed with RAPD using 230 10mer arbitrary primers. The results showed that for the majority primers, the bands were same between the parents. Primer S86 (GTGCCTAACC) generated polymorphic bands, the fragment at 2000bp unique to the parent A, and the fragment at 1000bp unique to the parent B.The two fragments were complementary and stable in the F1 generation. So seed purity identification of "Xiyuan No.6" were practiced with this primer.4.2 Analysis of stability of the seed purity identification system(1)Selected 20 cabbage "Xiyuan No.6" at random ,then extracted DNA from them..The resultshowed that 4 plants not belong to "Xiyuan No.6" after analyzing their DNA with RAPD.The purity of this group is 80%.(2)Identification of "Xiyuan No.6" mixed with its parents and other varieties of cabbages Mixed parents and other varieties of cabbages without maker in doubtless"Xiyuan No.6".After analyzing their DNA with RAPD, compare with the purity identification fingerprint.,we can identify"Xiyuan No.6".and other cabbages varieties very easily.It proves that it is practical and reliable to use this primer to identify the purity of "Xiyuan No.6".