Tne Genetic Relationship Of Ornamental Peach And That Of Peach Rootstocks By Ssr Markers

In this study, SSR was used to appraise34ornamental peach,7relatives,1P. persica (L.) Batsch and24peach rootstocks conserved in National Peach Germplasm Repository in Nanjing. The results went as followes:Firstly, The results of genetic relationship of Ornamental peach identified by SSR. In order to analyze their genetic diversity and phylogenetic relationship, a collection of34ornamental peach varieties,7relatives and1P. persica (L.) Batsch have been screened with16SSR primer pairs distributed on eight linkage groups on Prunus reference map.124bands were amplified by16informative and reliable primers, the percentage of polymorphic bands (PPB) was87.99%.When clustered by UPGMA, eight group were formed. Group Ⅰ were consisted of "12P. persica var.duplexs "; Group Ⅱ were consisted of "9P. persica var. duplex,5P. persica var. pendula and3P. persica var. densa Makino "; Group Ⅲ had only "Juhuatao"; Group Ⅳ, Ⅴ were "P. ferganensis (Kost. et Riab) Kov. et Kost.’"Huangjinmeili", respectively; GroupVI were consisted of "Three pillar peach"; Group Ⅶ were consisted of "7Relatives and1P. persica (L.) Batsch"; Group Ⅷ had only "P. mira Koehne.".12P. persica var.duplexs were classified in Group Ⅰ, This results demonstrated that grow habit probably is a hierarchy in ornamental peach systematic.9P. persica var. duplex,5P. persica var. pendula and3P. persica var. densa Makino were clustered into Group Ⅱ, which indicated these cultivars had much close relationship and different growth habit were possible involved into each other during their breeding and developing process. Juhuatao was clustered into Group Ⅲ by itself, It is possible that this cultivar originated independently and might be an important germplasm source for further ornamental peach breeding, this variety is advised to protected as special germplasm. Three pillar peaches germplasm of Group Ⅵ were imported, which have a narrow grow habit, columnar shape, clear trunk, branches straight. SSR results show that these three pillar peaches clustered together, indicating pillar peach tree type is unique, same with the morphological classification. All of the P. persica var. duplex tested were divided into4group in the phylogenetic dendrogram, this showed the origin of P. persica var. duplex is polynary.Secondly, the results of genetic diversity and relationship of peach rootstocks identified by SSR.In order to study genetic diversity and relationship of peach rootstocks germplasm, A collection of24peach rootstock have been screened with17SSR primer pairs distributed on eight linkage groups on Prunus reference map.153bands were amplified by17informative and reliable primers, the percentage of polymorphic loci was94.87%and the polymorphic bands amplified with each arbitrary primer totaled2-15.When clustered by UPGMA, seven group were formed. Group Ⅰ were consisted of18P.persica(L.)Bastch and was divided into two subgroup. Subgroup Ⅰ-1included peach rootstock cultivars of U.S.A., France, Japan and Canada. These cultivars interveined each other. Subgroup1-2consisted of Siberia C and Chinese rootstocks. Group Ⅱ-Ⅶ were "P. davidiana (Carr.)Franch.’zhouxingshantao’","P. potaninii Batal.","P. davidiana (Carr.)Franch.’baihuashantao’","P. davidiana (Carr.)Franch.’honghuashantao’","P. kansuensis Rehd.","P. mira Koehne.", respectively.The peach rootstock varieties of different countries of Subgroup Ⅰ-1have no clear boundaries, these cultivars interveined each other. It is possible that different countries’ peach rootstocks were involved into each other in modern breeding programs of these cultivars and have more opportunities for exchanging germplasm to accelerate penetration of different type of gene, Varieties differentiation become more complex. The similarity coefficient level of Subgroup Ⅰ-1is high, suggesting a narrow genetic diversity among these cultivars. This result supports the conclusion drawn by Scorza et al(1985) that the genetic diversity of peach has been further narrowed by using a few cultivars in modern breeding programs.Group Ⅱ-Ⅶ formed six remarkable outgroups to P.persica of Group Ⅰ, which indicates that peach wild speices were genetically distant from other peach rootstock cultivars from P.persica. It is possible that peach wild relatives propagated by seed and had little exchange of germplasm with other countries’ peach rootstocks.