The tree peony belongs to section Moutan of Paeonia, known as the 'King of Flowers' in China and has great ornamental, medicinal and economic value. In this study, 12 novel polymorphic microsatellite markers from Paeonia ostii were developed and characterized by constructing a simple sequence repeat (SSR)-enriched genomic library. In total, 42 alleles across 48 tree peony accessions were detected, with an average of 3.5 alleles per locus, the number of effective alleles ranged from 1.4 to 4.7 with an average of 2.4 per locus, the observed and expected heterozygosity per locus ranged from 0.333 to 1.000 (an average of 0.785) and from 0.298 to 0.795 (an average of 0.541), respectively. The polymorphism information content (PIC) varied from 0.257 to 0.794, with an average of 0.468. Shannon Index was ranged from 0.594 to 1.771 and the mean value was 0.906. Moreover, these markers can also be amplified in herbaceous peonies Paeonia lactiflora and Paeonia veitchii of section Paeon. A neighbor-joining (NJ) tree was constructed using the proportion of shared alleles coefficient to assess the genetic relationships among species and cultivars. In the NJ tree, the accessions in the section Paeon spanned the extremes of the dendrogram and were used as an outgroup. The accessions in the section Moutan primarily grouped into two clusters. In cluster I, Paeonia rockii and Xibei Group cultivars clustered into one branch, indicating that P. rockii was the main ancestor of the Xibei cultivars. P. rockii and its cultivars were closely related to Paeonia decomposita. All Zhongyuan Group cultivars, Paeonia x lemoinei hybrids and P. ostii formed clusterII. P. ostii grouped with Zhongyuan cultivars, indicating that P. ostii contributed significant genetic information to Zhongyuan cultivars. Zhongyuan cultivars and P. x lemoinei hybrids were divided into groups with various corresponding bootstrap values. Principal component analysis (PCA) based on gene frequency further illustrated these genetic relationships. PCA supported the results of the clustering analysis, and it is easily discernable that cultivars from the same group distributed together, while wild accessions with a close relationship to cultivars were distributed with the cultivars. The results show that these SSR markers are very powerful in studying genetic relationships and that they have the ability to cross-amplify in other Paeoniaceae family members. Furthermore, the new SSR markers will be useful tools in assessing genetic diversity, detecting quantitative trait loci (QTL) and finally in facilitating marker-assisted selection (MAS). (C) 2013 Published by Elsevier B.V.

Wild flowers,being colorful,beautiful and various,have higher ornamental values,and also have strong flexibility and resistance.They are very important flower resources and have important values in flower border design.On the foundation of investigation and study and the basis of the flower border design principles and some ornamental and ecological characteristics,the wild flowers investigated in Beijing Xiaolongmen Forestry Park in July,2011,have been analyzed and evaluated,and classified in three aspects,plant height,color and seasonal aspect,in order to provide reference and more materials for flower border design.

The genesis and differentiation into meristematic nodule of thin cell layer of(TCLs) petiole callus in modern tree peony 'Golden era' were studied.The results showed that there were four stages in the course of callus development,namely activation,division,formation and histodifferentiation.During activation,fascicular cambium cells were most notable,showing brown externally and bigger cells,clear and near-center nucleus internally.Meanwhile the starch metabolic enhanced.Cells kept division during the second stage division and led to the formation of callus in cambial area firstly and then in the region of cortex parenchyma cells.These callus tissues formed a compact cell cluster and the callus cells were characterized by dense cytoplasm,nucleus in center,small in volume and starch grains accumulated around the nucleus.However,callus proliferated at a slower rate during formation stage,only the peripheral callus cells which facing the medium kept division.At the last stage histodifferentiation,callus tissues differentiated into neoformed tracheary elements.Some of these tracheids organized as vascular centers and some specialized parenchyma cells could also act as centers.And then these centers were surrounded by loosely arranged,plastid-dense cell layers.This way,meristematic nodule formed which was thought to be potential in mass production.The result here can be used as a basis for further improvement of organ regeneration system for large-scale multiplication of tree peony.