Study On The Genetic Diversity And Evolutionary Relationship Of Wild Tree Peony In The Subsect.vaginate

The wild tree peony resources of Subsect.Vagintae are mostly unique germplasm resources in China and play an important role in maintaining tree peony biodiversity.However,the study of its genetic diversity and evolution relationship was not yet complete.In the present study,the phylogenetic systematics and genetic diversity of the wild tree peony species in Subsect.Vagintae(P.qiui、 P.jishanensis、 P.ostii 、P.rockii、 P.decomposita)were investigated using phenotypic traits,pollen morphology and SSR methods.The main results were as follows:(1)44 characters of 5 wild tree peony species were investigated.The trait correlation analysis,principal component analysis,population phenotype and Q cluster analysis were performed.And the results showed that the branching characteristics,date of blooming,flower shape,flower color,leaf shape and size provided good references for the classification and identification of wild tree peony species.Phenotypic analysis and Q clustering results showed that there were some differences within different populations of the same species.They were not completely clustered according to species or geographical distance,indicating that the phenotypic traits of each population could be affected by environmental factors of distribution area.(2)Pollen morphological characteristics of 27 different populations from 5 species indicated that pollen morphology had abundant similarities and diversity.They were all prolate or perprolate,medium size and 3-colporoidate,but their exine ornamentations were different,which reflected genetic diversity of different tree peony germplasms,and could also provide valuable basis for the study of genetic relationship and phylogenetic germplasm of wild tree penoy.In this study,exine ornamentation of wild tree peony species in Subsect vagiatae from P.jishanensis-P.qiui-P.ostii-P.rockii-P.decomposita were micro-foveolate,foveolate,fine-reticulate,reticulate,wide-reticulate,regulate-reticulate and regulate patterns,respectively;and the evolution was as following: P.jishanensis and P.qiui-P.ostii-P.rockii-P.decomposita.Based on the observation and comparison of pollen morphology of the same species from different habitats,the pollen grains had evolved diverse morphologies under varying environmental conditions.The results showed that the D/W of P.rockii subsp.atava populations in Longnan,Wenxian,Fengxian was larger than D/W of P.rockii subsp.rockii populations in Ganquan and Huangbaiyuan,which indicated that P.rockii subsp.atava had higher degree of evolution than P.rockii subsp.rockii.The exine ornamentations of two subspecies of P.decomposita were also different.(3)12 pairs of core primers of SSR markers were selected to tested genetic diversity of 37 materials and a total of 120 alleles were detected.The results showed that the effective numbers of alleles ranged from 1.7414 to 9.1862,and that the primer Shannon information index(I*)ranged from 1.2205 to 2.4495,and that Nei’s gene diversity ranged from 0.8911 to 0.4257.For the test materials,the effective allelic variation ranged from 1.500 to 2.560,with an average of 1.838;Shannon-Weaver(I)was between 0.347 and 1.007;and the percentage of polymorphic loci(PPL)ranged from 58.33% to 100%,with an average of 71.62%.According to the Nei’s genetic identity,UPGMA cluster analysis was performed on 37 peony populations.The results showed that 37 populations could be divided into 4 categories at the genetic distance of 0.40,and there were cross clusters among different species.In the cluster analysis of species or subspecies,P.jishanensis,P.qiui and P.ostii were clustered into one group.The two subspecies of P.rockii and the F1 individual derived from crossing between P.rockii and P.ostii were clustered into one category.And the two subspecies of P.decomposita were clustered together.The correlation coefficient of SSR molecular markers with phenotypic traits and pollen morphology was 0.426 and 0.316,respectively,showing a highly significant positive correlation,which indicated the consistency and effectiveness of the three clustering methods.