Molecular identification of Malus hupehensis (tea crabapple) accessions using simple sequence repeats

Abstract

The U.S. National Plant Germplasm System (NPGS) currently holds 36 separate accessions of the 'Yichang' clone of Malus hupehensis (Pamp.) Rehd. The 'Yichang' clone originally entered the United States in 1908 as seed collected for the Arnold Arboretum by E.H. Wilson near Yichang, Hubei Province, China. The original description of M. hupehensis omits fruit characters, and botanists frequently augment these omissions with descriptions of the 'Yichang' clone. Apomixis occurs in Malus, including M. hupehensis, and is strongly associated with elevated ploidy levels. Simple sequence repeats (SSRs) were used to characterize 65 accessions of M. hupehensis. To check for polyploidy, a set of M. hupehensis accessions was evaluated with flow cytometry. The simple sequence repeat phenotypes and ploidy information revealed the 'Yichang' clone under various accession names in arboreta. It was neither known nor suspected that the U.S. National Plant Germplasm System held many duplicate accessions of the 'Yichang' clone prior to their molecular characterization. Germplasm conservation decisions for Malus species can benefit from an increased knowledge of the genetic variation or lack thereof in naturalized populations and ex situ collections.