Genetic diversity and relatedness among ornamental purslane (Portulaca L.) accessions unraveled by SRAP markers

Abstract

Ornamental purslanes (Portulaca L.) are a popular annual bedding and container plant for landscaping. Little information is available concerning the genetic characterization of ornamental purslane resources thus far. The purpose of this study was to investigate the genetic diversity and relationships present in a collection of ornamental purslanes from Portulaca umbraticola and P. grandiflora cultivated in China, using sequence-related amplified polymorphism (SRAP) markers. The genotyping showed that 16 SRAP primer combinations totally produced 261 informative fragments and averaged 16.31 per primer combination. The major allele frequency and Nei's gene diversity was calculated at 0.78 and 0.31 across the loci, indicative of a moderate low diversity. Both unweighted pair group method with arithmetic average (UPGMA) clustering and a Bayesian-based approach apparently assigned the whole accessions into two sub-groups: P. umbraticola and P. grandiflora, well concordant with the botanical classification and flower type. The findings provide a brandnew understanding of genetic diversity and population structure present in ornamental purslane, and benefit a sound design of breeding programs in future.

Keywords: Genetic diversity; Population structure; Portulaca L.; Sequence-related amplified polymorphism marker.

Fig. 1

Representative accessions of the investigated ornamental purslanes from P. umbraticola (a–e) and P. grandiflora (f, g with a single flower; h, l with a double flower)

Fig. 2

Dendrogram of 38 ornamental purslane accessions clustering based on the SRAP marker-based Nei’s distance index. The bootstrap values larger than 50% are shown on corresponding clustering nodes. The accession codes on the right of the dendrogram refer to Table 1

Fig. 3

Genetic structure of the 38 ornamental purslane accessions, derived from STRUCTURE analysis, based on an admixture model with K = 2 (a), and K = 3 (b). Each entry is represented by a thin vertical line. The identified sub-groups are indicated in different colors. The accession numbers refer to Table 1