Sorting and identification of Rehmannia glutinosa germplasm resources based on EST-SSR, scanning electron microscopy micromorphology, and quantitative taxonomy

Abstract Rehmannia glutinosa Libosch. is a valuable medicinal and industrial crop, in the clinical use of traditional Chinese medicine has been a thousand years of history, grown widely in the central plain of China. Different cultivars have wide differences in crop yield and quality. Furthermore, long-term mixed cultivation has led to a serious confusion between Rehmannia glutinosa germplasms, which has significantly restricted the breeding of fine cultivars. In this study, 25 core Rehmannia glutinosa germplasms were collected and analyzed by scanning electron microscopy (SEM) to obtain micromorphology. Quantitative taxonomy was then used to identify the genetic relationship between the Rehmannia glutinosa germplasms. Forty agronomic traits, including 24 scanning electron microscopy (SEM) micromorphology traits, were chosen to construct the quantitative taxonomy dendrogram. In addition, expressed sequence tags (EST) derived microsatellite markers were also identified and validated in the 25 different Rehmannia glutinosa germplasms to confirm the genetic relationships. Based on a combination of these approaches, four new cultivars were discovered, and were given the standard names “Huaidihuang 01 2017, Huaidihuang 02 2017, Huaidihuang 03 2017 and Huaidihuang 04 2017” according to the international code of nomenclature for cultivated plants (ICNCP) (1995 edition). The study has provided important pollen and seed micromorphology data, as well as genetic diversity data, that can be used as basis for the scientific classification and identification of Rehmannia glutinosa cultivars. It also indicates the hierarchical status of the newly identified cultivars, which will help in protecting the germplasm resources, as well as in Rehmannia glutinosa introduction, cultivation, and breeding.