Tree peony has nine wild species, but the evolutionary relationship of them is still unclear. Here, a total of 274 specimens from 22 natural populations of nine wild species were collected, and their genetic diversity and similarity was analyzed based on Simple Sequence Repeats (SSR) molecular markers. A total of 106 alleles were generated based on 20 primers and with an average of 5.3 alleles per primer. Shannon's information index (I) ranged from 0.6333 to 1.7842, and the average of Nei's genetic diversity coefficient (H) was 0.5771. Polymorphism Information Content (PIC) value varied from 0.29 to 0.77, ten of these primers had high polymorphism (PIC $\ge$ 0.50). All the above genetic parameters of primers reflect more rich genetic diversity information compared with other researches using SSR molecular markers to study the genetic diversity of tree peony wild species. At the population level, the lowest and highest degree of genetic diversity occurred in Paeonia ludlowii-P1 and P. delavayi-P3 population, respectively. Whereas at species level, the genetic diversity of 9 wild peony species was as follows: P. lutea > P. delavayi > P. rockii > P. qiui > P. ostii > P. decomposita > P. potaninii > P. spontanea > P. ludlowii. Furthermore, cluster analysis at species level divided the nine wild tree peony species into two branches. In branch I, the closest phylogenetic relationship was found between P. ostii and P. rockii, followed by P. spontanea, P. qiui, and P. decomposita. In branch II, the closest relationship occurred between P. lutea and P. delavayi, followed by P. potaninii and P. ludlowii. Clustering results supported the division of tree peonies into two subsects (Delavayanae and Vaginatae), it also supported P. potaninii and P. ludlowii as independent species. The results provided novel insight into the genetic diversity and phylogenetic relationship of nine wild tree peony species. It will help formulate comprehensive protection measures of wild germplasm resources and select proper parents for distant hybridization in the future.

牡丹有九个野生种，但它们之间的进化关系尚不清楚。在这里，共收集了来自 9 个野生物种 22 个自然种群的 274 个标本，并基于简单序列重复（SSR）分子标记分析了它们的遗传多样性和相似性。基于 20 个引物，共产生 106 个等位基因，每个引物平均有 5.3 个等位基因。香农信息指数(I)的范围为0.6333～1.7842，内氏遗传多样性系数(H)的平均值为0.5771。多态性信息含量 (PIC) 值从 0.29 到 0.77 不等，其中 10 个引物具有高多态性 (PIC) $\ge$ 0.50）。上述引物遗传参数与其他利用SSR分子标记研究牡丹野生种遗传多样性的研究相比，反映了更丰富的遗传多样性信息。在种群水平上，Paeonia ludlowii-P1和P. delavayi -P3种群的遗传多样性最低和最高。而在物种水平上，9种野生牡丹的遗传多样性为：P. lutea > P. delavayi > P. rockii > P. qiui > P. ostii > P. decomposita > P. potaninii > P. spontanea > P . 卢德洛伊. 此外，物种水平的聚类分析将九种野生牡丹树种分为两个分支。在分支我，最近的亲缘关系之间发现P.凤丹和P.牡丹，其次为P. spontanea，P. qiui和四川牡丹。在分支II中，P. lutea和P. delavayi之间的关系最密切，其次是P. potanii和P. ludlowii。聚类结果支持将牡丹分为两个亚类（Delavayanae 和 Vaginatae），也支持P. potaninii和P. ludlowii作为独立物种。结果为九种野生牡丹树种的遗传多样性和系统发育关系提供了新的见解。这将有助于制定全面的野生种质资源保护措施，并为未来的远缘杂交选择合适的亲本。