Studies On Genetic Diversity And Relatives Of Radish Germplasm Resource

Radish is an important vegetable and the germplasm resource is very abundant in China. The study on the genetic diversity of radish can benefit the conservation, classification, identification, genetic enhancement and effective utilization of the radish germplasm resource. Molecular marker, which can detect the genetic diversity at DNA level, is a powerful tool to study genetic diversity. RAPD and AFLP markers have been popularized for their simplicity, rapidity and non-specialty among different genera. In this study, the genetic diversity in 56 radish accessions from different countries or regions was assessed using morphological, RAPD and AFLP markers, and the genetic relationship among the accessions was revealed by systemic clustering analysis, principal components analysis and principal coordinates analysis at various level. The main results were as follows:1. In morphological assessment, the average diversity index among the accessions was 0.80 based on the data of 10 morphological characters. The 56 accessions were clustered into 5 groups based on the morphological data. The results of principal components analysis showed that color, characters of root and leaf are the decisive factors affecting radish germplasm classification according to morphological characters.2. A total of 109 distinct bands were detected with 12 informative RAPD primers among 56 radish accessions. Of them, 72 bands (62.9%) were polymorphic. The average heterozygosity of RAPD loci was 0.289. 56 accessions were clustered into 7 groups based on the RAPD data by the method of clustering analysis, and 3 groups by the method of principal coordinates analysis.3. A total of 327 distinct bands were detected with 8 pairs of informative AFLP primer among 56 radish accessions. Of them, 128 bands (38.1%) were polymorphic. The average heterozygosity of AFLP loci was 0.362. 56 accessions were clustered into 9 groups based on the AFLP data by the method of clustering analysis, and 4 groups by the method of principal coordinates analysis.4. The study on the genetic diversity of 56 radish accessions was made by integrating the RAPD and AFLP data. The 56 accessions were classified into 9 groups with method of systemic clustering analysis and 4 groups with method of principal coordinates analysis.5. Comparison of the data obtained by morphological marker and molecular makers was made by the method of Mantel test. The r correlation value scope was 0.230-0.255 between the morphological marker and molecular markers, while the r correlation valuebetween RAPD and AFLP marker is 0.662.6. Comparison of the results on the genetic diversity by the two types of molecular maker was made. RAPD maker had higher polymorphic rate and lower average heterozygosity than APLP maker. Both of the makers were suitable for the study of radish genetic diversity. In this study, the dendrogram of cluster analysis obtained by RAPD marker was similar with that of AFLP marker.7. All the results above confirmed that the 56 radish accessions could be classified into 7 groups. Fekete, Yizhehengding, Xinlimei, Guoguang were classified into one group respectively. 9 accessions from Europe were classified into one group. The accessions from Korea were classified into one group. The domestic accessions were classified into one group. The domestic accessions exhibited high relatedness of root color within each sub-group. The accessions with red-coated root were nearly put into one sub-group, while the accessions with white and green-coated or white-coated root were put into the other sub-group.