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

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, NA = 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.

Genetic Diversity of Paeonia rockii (Flare Tree Peony) Germplasm Accessions Revealed by Phenotypic Traits, EST-SSR Markers and Chloroplast DNA Sequences

“…Because the phenotype is the result of the interaction of genotype and external environment and the diversity of phenotypic traits is the manifestation of genotype difference in morphology, the phenotypic variation in the population mainly depends on the genotype difference when all accessions used in this study were grown in the same condition. In FTP, Pang et al [59] reported phenotypic variation coefficients ranging from 10% to 30% based on 32 traits of 150 accessions, but Wu et al [60], on the diversity of 29 quantitative traits of 462 accessions, found that the coefficient of genetic variation was 9.52-112.1%. By the genetic diversity of 28 quantitative traits of 180 accessions, this study revealed a genetic variation coefficient of 12.33-108.73%, which was similar to Wu et al [60].…”

“…In FTP, Pang et al [59] reported phenotypic variation coefficients ranging from 10% to 30% based on 32 traits of 150 accessions, but Wu et al [60], on the diversity of 29 quantitative traits of 462 accessions, found that the coefficient of genetic variation was 9.52-112.1%. By the genetic diversity of 28 quantitative traits of 180 accessions, this study revealed a genetic variation coefficient of 12.33-108.73%, which was similar to Wu et al [60]. As the plants used both by Wu al.…”

“…In FTP, Pang et al [59] reported phenotypic variation coefficients ranging from 10% to 30% based on 32 traits of 150 accessions, but Wu et al [60], on the diversity of 29 quantitative traits of 462 accessions, found that the coefficient of genetic variation was 9.52-112.1%. By the genetic diversity of 28 quantitative traits of 180 accessions, this study revealed a genetic variation coefficient of 12.33-108.73%, which was similar to Wu et al [60]. As the plants used both by Wu et al and by this study are widely selected and collected from the main cultivation area of the FTP, Gansu province (Figure 2), we felt that the accession population of this study should be large enough to represent the overall situation of FTP as a germplasm resource.…”