Studies On Genetic Diversity Of Tobacco Germplasm Resources By SSR Marker, ISSR Marker And Agronomic Trait

In this study, we analyzed the genetic difference among72tobacco germplasm resources based on SSR and ISSR marker and proved up the genetic diversity and genetic relationships among them. Meanwhile,20agronomic traits of24tobacco germplasm resources were assessed by phenotypic character. Intrinsic quality among these agronomic traits was investigated with variance analysis, principal component analysis and cluster analysis. The main results of SSR markers, ISSR markers and agronomic traits were as follows:1. Using variance analysis to analysis the agronomic traits of24tobacco germplasm resources, the experimental results indicated that their coefficient variation ranged from0.089to0.289. There was greatly difference among these tobacco germplasm resources which were abundant in genetic diversity.2. Through Principal component analysis, five main components was selected whose cumulative contribution had reached80.6%. The results revealed that the resources of the variation of germplasm were from leaf number, length of leaves, width of leaves, angle between stem and leaf, stem girth and plant high. The result of cluster analysis was similar to the result of principal component analysis. Length of bottom leaves, length of middle leaves, length of top leaves and leaf number interacted intimately. Width of bottom leaves, width of middle leaves, width of top leaves and angle between stem and leaf had close contact between each other. According to the result of scatter diagram, although agronomic trait can provide some references for breeding, it can not determine relative relationships among tobacco germplasm resources.3. The genetic diversity and genetic relationship were studied by SSR markers for72tobacco varieties from the molecular level.167bands were detected with29primers, of which151bands were polymorphic bands,5.2polymorphic bands were amplified by each SSR primer, and the percentage of polymorphic bands was90.4%. The genetic distance among72tobacco germplasm resources was0.0105to0.4421, with an average of0.244. The genetic distance among flue cured-tobacco ranged from0.0211to0.4000, while it ranged from0.0105to0.4421among sun-cured tobacco.4. ISSR analysis was performed by11polymorphic primers to72tobacco varieties. Results showed that94bands had emerged, and there were83polymorphic bands, the proportion of polymorphic bands was91.5%. Each ISSR primers could amplify8.55polymorphic bands. The genetic distance among72tobacco germplasm resources was0.043to0.613, and the average genetic distance was0.244.5. Depending on the cluster diagram based on the genetic distances estimated by SSR marker and ISSR marker, we could find.(1) The sun-cured tobacco and flue cured-tobacco could be classified into two groups.(2) In the flue cured-tobacco, the domestic germplasm resources and imported germplasm resources couldn’ t be entirely separated from each other. The first one showed that there was significantly genetic difference in the genetic background in tobacco cultivars. The second one revealed that:in traditional breeding, selecting parental combination by different geography origin was not perfectly. The future breeding should not be limited to geography origin and should depend on the genetic difference from the molecular level.6. Agronomic characters, SSR marker and ISSR marker revealed the genetic diversity of the tobacco germplasm resources from different perspectives. The resulted could not show that one method could be replaced by others. The mutual combination and mutual synthetic analysis of these methods could reflect the genetic nature of tobacco varieties.