| Subgen.Yulania(Spach)Reichenb.is deciduous trees or shrubs species in Magnoliaceae.It is a kind of precious trees with magnificent tree shape,beautiful flowers,and wide range of uses.Due to its complex genetic background and abundant germplasm resources,it is difficult to correctly classify genetic relationships based solely on morphological characteristics.Magnolia sinostellata is a new species of Magnolia in Magnoliaceae.Because of its narrow distribution area,extremely small population,and low seed setting rate,M.sinostellata has been listed as an endangered plant in Zhejiang province.Coupled with environmental destruction and deforestation,wild M.sinostellata populations have been destroyed to a certain extent,which affect their genetic diversit M.In order to study the endangered mechanism of M.sinostellata and provide theoretical basis for the subsequent conservation and utilization of resources,this study has systematically studied the genetic diversity of four geographical populations of M.sinostellata using EST-SSR molecular marker technolog M.At the same time,the selected primers of M.sinostellata were used to analyze the genetic diversity and relationship of Magnolia genus in order to provide molecular theoretical basis for the identification of germplasm resources of Magnolia.The main results are as follows:1.Assembling into 110,644 unique sequences with 90.83 Mb total nucleotides,in which 25,472 SSRs were identified,with the average frequency of 23.02% and average density of 3.57 kb and the motifs length of 12-25 bp,by using SSR finding soft.Mono-nucleotides(33.53%)and di-nucleotides(42.08%)appeared to be the most abundant repeated motifs.2.With natural populations distributed in such main distribution areas of M.sinostellata as Jingning County(JN),Songyang County(SY),Liandu County(LD)and Yandang County(YD),102 samples from such populations were analyzed with 23 pairs of EST-SSR polymorphic primers.It was showed that 204 alleles amplified by the 23 primers.The expected heterozygosity(He)?Shannon information index(I)and Nei's gene diversity(h)were 0.6764,1.2489 and 0.6731,respectively;gene flow(Nm)and coefficient of genetic differentiation(Fst)were 0.8024 and 0.2375.Using the genetic diversity index as the evaluation index,the genetic diversity of JN population was the highest(h=0.6243,I=1.1514),and the YD population was the lowest(h=0.2536,I=0.3879).The 4 populations were classified into 3 groups based on the similarity coefficient at 0.6300.3.30 pleomorphic loci were screened from M.sinostellata,and the polymorphism information content(PIC)of 30 primers was ranged from 0.2373-0.7795.The genetic diversity and relationship of Magnolia were analyzed with 30 primers.It is showed that The Shannon's information index(I)was ranged from 0.5010-1.0969,with an average of 0.9256.The Nei's genetic diversity(h)was ranged from 0.2540-0.6655,with an average of 0.5565.The result of UPGMA cluster analysis was basically similar with the principal coordinate analysis,from which 21 materials could be divided into 4 groups: M.×soulangeana Soul.–Bod.taxa,M.denudate taxa,M.biondii taxa,and M.acuminate taxa.These results suggested that M.sinostellata had a high genetic diversit M.Genetic differentiation was apparent among populations,and gene drift increased within populations.Enhancing species abundance and taking some conservation measures should be favorable to saving the species.Meanwhile,Magnolia has a close evolutionary relationship and rich genetic diversit M.EST-SSR molecular markers can be used for identification of germplasm resources,and provide important basis for subsequent genetic map construction and molecular marker-assisted breeding. |
PDF Full Text Request