Analyse The Genetic Diversity Of The Populus And Salix By SSR And ITS Sequences

Poplar and willow belonging Populus and Salix,they are very important hardwood species and energy forest tree species in the world,poplar and willow also have high economic and ecological value and also a good study material on forest genetics.Poplar and willow prone to natural variation and it is very prone sexual reproduction and as exual reproduction,it is difficult to identify some species by phenotypic.Therefore,with the continuous development of biotechnology,we need study the genetic relationships and genetic diversity of these species at the molecular level of DNA.This test uses SSR markers,we select 32 polar clones and 49 Salix clones as test materials,genetic diversity and genetic relationship are analyzed of these clones,and by ITS sequence analysis that we established phylogenetic tree of Populus and Salix,in addition,the ITS and SSR markers were analyzed about correlation,results are as follows:(1)From 28 pairs of SSR we selected 13 SSR primers,which showed efficient amplification and were used for 32 Populus clones in the experiment.We obtained a total of 58 DNA bands,58 bands were found to be polymorphic,accounting for amplification with 100% of the total.The calculating results show that the similarity coefficient of 32 Populus clones range between 0.0565～0.7061 showed high genetic diversity,We can see,SSR molecular marker technology can separate different clones and to reveal the relationship between clones.Through cluster analysis,these clones can be divided into three clusters,it is Populus,Aigeiros and Tacamahaca.And the clustering results are consistent with the results of traditional taxonomic,it is reliability to identify different species of populus by SSR molecular markers.(2)49 ancient Salix matsudana Koidz was analyzed with 13 pairs of primers,a total of 41 DNA bands were amplicated,30 bands among which showed average polymorphism ratio of 73.17%.While 49 ancient Salix matsudana Koidz materials are divided into seven regions,and then these materials are analyed by POPGENE 32 software,the cluster analysis showed that the seven regions were closely correlated with geographical locations;the clustering results show that the similarity coefficient of 49 ancient Salix matsudana Koidz range between 0.1123～0.5863,showed high genetic diversity.What’s more,the results of cluster analysis of these 49 individual plants,showed that these 49 old trees planted by the different time from different clones,cluster tesults presented hybridity associated with of low relationship with regions.(3)In the study,12 Populus clones and 4 Salix clones′ length of ITS region sequence is 663.0 bp in average.According to these samples in ITS region sequence,the base frequencies remains different in different species,the proportion of A between17.14%～17.81%,the proportion of T between 16.79%～18.05%,the proportion of G between 31.93%～32.73%,the proportion of C between 31.89%～33.43%,the content of G+C is from 64.36%(zhaiguan)to 65.66%(Populus simonii Carr.).Populus and Salix were constructed phylogenetic tree using neighbor-joining and the results may reflect the genetic relationship between all clons,and so it is feasible to identify and analyze the resources of Populus and Salix by ITS.(4)12 poplar clons were analyzed with SSR molecular markers and ITS technologies and the results showed no difference between the two methods in the basic clustering,but the SSR marker more accurater than ITS technology in subtle clustering,after data analysis,we know the number of sexual relations about SSR and ITS is 0.5933 and it reached a significant level,it indicated that there are some difference and less correlation between SSR and ITS.