Core collection construction and evaluation of the genetic structure of Glycyrrhiza in China using markers for genomic simple sequence repeats

Glycyrrhiza is a widely used traditional Chinese herb with medicinal values. In order to avoid handling a large number of collections with redundant genetic information, it is necessary to construct a core collection with minimal accessions and maximal genetic diversity. In this study, the initial collection consisted of 736 accessions from four species, each of which was analyzed using SSR markers. The advanced M (maximization) strategy of PowerCore was utilized to select 124 accessions for the core collection. The core collection retained 100% of the alleles of the initial collection, and there was no significant difference regarding the genetic diversity parameters compared to the initial collection. PCoA and AMOVA also showed that the core collection has a similar genetic distribution. NJ and STRUCTURE analyses showed that the core collection can be divided into three groups: The first group is represented by the majority of Glycyrrhiza uralensis Fisch.; the second group is represented by Glycyrrhiza inflata Batalin and Glycyrrhiza glabra L.; and finally, the third group is represented by Glycyrrhiza pallidiflora Maxim. The results indicate that the core collection is an effective tool for representing the genetic diversity of the initial collection. The core collection also provides a useful primary resource to improve the conservation of genetic diversity and to improve Glycyrrhiza breeding.