Dissection of Allelic Variation Underlying Floral and Fruit Traits in Flare Tree Peony (Paeonia rockii) Using Association Mapping

Xin Guo; Chunyan He; Fangyun Cheng; Yuan Zhong; Xinyun Cheng; Xiwen Tao

doi:10.3389/fgene.2021.664814

Dissection of Allelic Variation Underlying Floral and Fruit Traits in Flare Tree Peony (Paeonia rockii) Using Association Mapping

Front Genet. 2021 Aug 11:12:664814. doi: 10.3389/fgene.2021.664814. eCollection 2021.

Authors

Xin Guo^{1

2

3

4

5}, Chunyan He^{1

2

3

4

5}, Fangyun Cheng^{1

2

3

4

5}, Yuan Zhong^{1

2

3

4

5}, Xinyun Cheng⁶, Xiwen Tao⁶

Affiliations

¹ Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, China.
² Peony International Institute, School of Landscape Architecture, Beijing Forestry University, Beijing, China.
³ Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, Beijing Forestry University, Beijing, China.
⁴ Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University, Beijing, China.
⁵ National Engineering Research Center for Floriculture, Beijing Forestry University, Beijing, China.
⁶ Beijing Guose Peony Technology Co. Ltd., Beijing, China.

Abstract

Allelic variation in floral quantitative traits, including the elements of flowers and fruits, is caused by extremely complex regulatory processes. In the genetic improvement of flare tree peony (Paeonia rockii), a unique ornamental and edible oil woody species in the genus Paeonia, a better understanding of the genetic composition of these complex traits related to flowers and fruits is needed. Therefore, we investigated the genetic diversity and population structure of 160 P. rockii accessions and conducted single-marker association analysis for 19 quantitative flower and fruit traits using 81 EST-SSR markers. The results showed that the population had a high phenotypic diversity (coefficients of variation, 11.87-110.64%) and a high level of genetic diversity (mean number of alleles, N _A = 6.09). These accessions were divided into three subgroups by STRUCTURE analysis and a neighbor-joining tree. Furthermore, we also found a low level of linkage disequilibrium between these EST-SSRs and, by single-marker association analysis, identified 134 significant associations, including four flower traits with 11 EST-SSRs and 10 fruit traits with 32 EST-SSRs. Finally, based on the sequence alignment of the associated markers, P280, PS2, PS12, PS27, PS118, PS131, and PS145 may be considered potential loci to increase the yield of flare tree peony. These results laid the foundation for further analysis of the genetic structure of some key traits in P. rockii and had an obvious potential application value in marker-assisted selection breeding.

Keywords: SSR markers; association mapping; flare tree peony (P. rockii); floral and fruit traits; linkage disequilibrium.