Application Of Molecular Markers In Pear Transmission Path And Germplasm Identification

Pear is an important temperate fruit tree species,which distributes all over the world.Because of its wide ecological climate adaptability and self-incompatibility,pear shows abundant germplasm resources and genetic diversity.Especially the artificial selection and breeding of germplasm resources in recent 100 years have made the hybrid recombination of germplasm resources,and more new hybrid varieties have been bred.It is impossible to use traditional diversity identification methods to meet the large number of pear varieties,molecular marker technology has shown great superiority in the identification of germplasm resources.Therefore,this study used molecular markers of pear to carry out the preliminary exploration of pear transmission path,identification of distant hybrids between pear and apple,and identification of genetic relationship of cherry germplasm resources,which provided valuable reference for exploring and utilizing pear and cherry germplasm resources and breeding research.The specific results are as follows:1.In order to explore the propagation path of pear in China,through consulting ancient and modern literature,historical records,local chronicles and other materials,and combining the theories and methods of history,molecular biology and other disciplines,the dissemination path of pear in China was preliminarily explored and conjectured:pear originated in the southwest of China,and the early dissemination mainly relied on non-biological factors such as water flow,wind.Biological factors such as reptile and birds are transmitted.The Yangtze River and the Yellow River are two important rivers that breed primitive agriculture in China.Pear fruits may be carried by human beings because of their edibility and spread from southwest to Eastern China.In this study,genome-wide re-sequencing of 75 ancient local varieties in the Yangtze and Pearl River valleys was carried out.The transmission path of pear from southwestern China along the Yangtze River valley was validated by genetic population structure characteristics.At the same time,it was found that the genetic background of Japanese sand pear was similar to that of Chinese sand pear in the Yangtze River valley,and probably originated from a common ancestor.2.In order to identify 311 Distant Hybrids of pear and apple,seven pairs of specific primers which can amplify specific bands only in pear or apple were screened by using specific molecular marker technology and specific gene sequence fragments of pear and apple.Through seedling identification,7 distant hybrids of pear and apple were successfully identified（2.3%）.Among them,1 was ’Malus domestica Borkh c.v.starking’×’Cornice’,3 were ’Golden Delicious’ × ’Dangshan Suli’,3 were ’Malus domestica Borkh.’Fuji’ × ’Comice’.3.In order to explore whether the SSR primers of pear can be applied to the identification of genetic relationship of cherry varieties,46 cherry varieties were identified by using 6 pairs of SSR primers of pear,and the genetic relationship of 46 cherry varieties was identified.The similarity coefficients among 46 cherry germplasms ranged from 0.65 to 0.98.The results showed that SSR primers of pear could be used to identify the genetic relationship of cherry cultivars belonging to Rosaceae,The markers had certain interspecies transferability.