Genetic Diversity Analysis Of Non-heading Chinese Cabbage Using SSR Markers And Agronomic Traits

The germplasm resources of non-heading Chinese cabbage were very rich, they had high quantity and complex type. However, with the popularity of the market on a few high yielding varieties, the germplasm resources were gradually single. In order to excavate the genetic potential of non- heading Chinese cabbage, make full use of germplasm resources, and provide the basis for breeding, we study 59 samples of non-heading Chinese cabbage at seeding stage and maturity stage, 12 quantitative traits and 8 quality traits were researched, the genetic diversity and genetic structure were studied by SSR markers. The results showed:1. The morphological traits 59 non-heading Chinese cabbage materials were observed at seedling stage, the quantitative trait variation coefficient was between 20.69-71.68%, the average value was 34.30%. The variation coefficient of leaf weight and plant weight was more than 50%, plant weight was the biggest and leave width has the smallest variation coefficient. The diversity index of waist coarseness and plant width were biggest(2.93). The variation coefficient of waist, foliar luster, leaf wrinkle and lobed leave was more than 50%, The diversity index of leaf color was biggest(2.58). it showed that the morphological traits had abundant variation. The principal component analysis showed, phenotypic traits at seedling stage were integrated into the four principal components, the cumulative contribution rate was 80.09%, Traits about plant size and yield had the highest contribution percentage(57.26%), it indicated that this part of the characters had breeding potential. The tested non-heading Chinese cabbage was divided into 3 categories according to the morphological characters at seedling stage. group I was all B. campestris which had wide leaf and waist, group III was all Wuta Tsai, and group II is a mixed population, both materials in group I, laciniata materials and high white terrier were in it. This indieated there were relative relationship between B. campestris var. communis and other types of non-heading Chinese cabbage..2. The quantitative traits variation coefficient were between 17.80%-63.39%of 59 non-heading Chinese cabbage germplasm at mature period, the average value is 34.90%, leaf number had a maximum coefficient variation, plant width had the minimum coefficient variation. The diversity index of petiole width was biggest(2.99), The diversity index of leaf number was smallest(1.74). The variation coefficient of lobed leave(246.62%) and foliar luster(174.49%) was the biggest, The diversity index them were small(0.61and1.18), The diversity index of leaf color was biggest(2.62). The variation of the morphological characters at mature stage is higher. Principal component analysis showed that the phenotypic traits of maturity was integrated into seven main constituents, the cumulative contribution rate was 82.22%, basal width, leaf weight, petiole width had the highest rate( 27.99%). This is similar to the results of seedling stage, basal width, leaf weight about plant size and yield had great potential for improving breeding. The clustering result showed that the reference materials could be clustered into 5 groups. Group I were almost B. campestris, it also can be divided into two categories, one with waist and wide materials; the other one does not have a waist, round leaves the bar high white material. Group II was laciniata materials. Group III is 1 Japanese jingshuicai. The group IV was 2 Wuta Tsai. Group V was a kuaicai.3. The correlation analysis of morphological characters of non-heading Chinese cabbage at seedling stage and mature stage was studied. The results showed that the correlation coefficients of leaf color, petiole color, foliar luster, leaf wrinkle, leaf margin folding were all above 0.8, leaf color and petiole color could up to 90%. It indicated that the two traits could be observed in the early time; waist width and leaf number characters must be choosed in the late tine because of the low correlation coefficient.4. 39 primers which were clear and polymorphic were screened out from 120 primers by five materials with clear, of detection, and 104 alleles were detected from 59 non- heading Chinese cabbage by this 39 SSR primers, the average for each marker 2.67 alleles were amplified from each primer in average. PIC value of makers were between 0.184-0.734,which was with an average 0.474. The average PIC value 0.474. the clustering analysis of 59 non- heading Chinese cabbage was researched and the results showed that: the test of 59 samples of materials can be classified into 3 categories, group I was almost all B. campestris. It can also be divided into two small categories, one had width leaf and waist; the other one were materials which had round and slender leaf and did not had waist. Subgroup I also included a Wuta Tsai and a purple caitai. Group II includingmaterials which werelaciniata and slender waist. The group also included one copy of Wuta Tsai and 3 kuaicai. Group III is the 1 Japanese jingshuicai, this was same with the result of morphological clustering results.