Study On Genetic Diversity Of Chinese Traditional Cultivars Of Tree Peony

Tree peony (Paeonia suffruticosa), which is a very popular traditional ornamental plant inChina and in the world, has varitable form and type, rich colors and long cultivation history. Inthis study, the distinctness,uniformity and stability in34traditional cultivars of Paeoniasuffruticosa Andr. were observed. Genetic diversity in34traditional cultivars and40moderncultivars were assessed using SRAP, ISSR, morphology and features of chromosome wereanalyzed for the first time. Moreover,the genetic relationship among the accessions wasrevealed by cluster analysis at various levels.The main conclusions were as follows:1In a two-year open field observation, five qualitative binary characters, twenty-onequalitative polymorphic characters and eight quantitative characters of34traditional cultivarsof Paconia suffruticosa Andr were analyzed, in terms of their distinctness, uniformity andstability. The results indicated that although the qualitative binary characters and the qualitativepolymorphic characters of all cultivars displayed good uniformity, there was a lack ofuniformity in the quantitative characters due to the influence of environment factors. Mostcultivars showed satisfying stability of their qualitative characters, but the variation ofquantitative characters was significant. Four qualitative binary characters and nineteenqualitative polymorphic characters were screened for the comparison of cultivars' distinctnessand the analysis of genetic diversities.2Thirty-four traditional cultivars of tree peony were selected to analyze the features ofchromosome, using squash method. Furthermore, according to Stebbins theory of thekaryotypic evolution as well as the method of coding of cladistics,4significant characters wereanalyzed. The results suggested that each material was diploid with10chromosomes exceptthat 'Shou An Hong'was triploid with15chromosomes；the karyotype formulas mostly were2n=6m+2sm+2st. The relationship between 'Dou Lv' and 'Yao Huang','Lan Tian Yu' and'Zhao Fen', which all belong to crown form, were the closest. But there were the maximual karyotype resemblance-near coefficient (0.8808), and the minimum evolutionary distance(0.1595) between 'Bai Yu' and 'Wei Zi' which both also belong to crown form, indicated thewidest genetic relationship. The chromosomal differentiation of crown form, chrysanthemumform, crown proliferate-flower form and rose form were high. The karyotypes of the cultivarswith different flower colors were similar. The cultivars with the same color system had similarevolution levels. The darker cultivars were more evolutional than the lighter ones. Theimportance of karyotype parameters was A.A.R> A.sk%> Lt/St> P.C.A%.3In this paper,we have determined the procedure of SRAP-PCR, optimized SRAPreaction mixtures and selected26pairs of primers with abundant polymorphism above70%.And we also assessed genetic diversity in34traditional cultivars and40modern varieties.Theresults were consistent with the taxonomy based on the flower type. Cultivars with the samecolor usually belong to one cluster, but part of the results was inconsistent with that based onflower color. Chrysanthemum form and rose form had a close relationship, and the geneticdifference between high polyphyll and low polyphyll was obvious. There was a trend of towerflower and single flower belonging to different cluster.4The results analyzed by ISSR were partly consistent with SRAP, only had tinydifference. The numbers of bands generated by ISSR was smaller than that by SRAP, but thepolymorphic rate was higher. We found that 'Zhi Hong','Ling Hua Zhan Lu','Yu Hou FengGuang' and'Yu Mei Ren','Fen Mian Tao Hua' were gathered for a class. The significantcorrelation between the genetic distance of ISSR and SRAP showed that these two molecularmarkers were feasible to research the genetic relationship among peony species.5Four clustering methods reflected similar genetic relationships among34traditionalcultivars. The results of3molecular markers had significant correlation. The results analyzedby the intergrated data from SRAP and ISSR were similar with SRAP, but that of ISSR weresimilar with that of morphology. Based on the gray relational and analytical method, therelational level among SRAP, ISSR, intergrated data from SRAP and ISSR and morphologycluster dendrogram was studied. The relational level between morphology and SRAP was highest. Phenotypic database of17traditional cultivars in core collection and8traditionalcultivars in primary core collection were finally established.