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

The U.S. National Plant Germplasm System (NPGS) currently holds 36 separate accessions of the 'Yichang' clone of Malus hupehensis (Damp.) Rehd. The 'Y ichang' clone originally entered the United States in 1908 as seed collecte d for the Arnold Arboretum by E.H. Wilson near Yichang, Hubei Province, Chi na. The original description of M. hupehensis omits fruit characters, and b otanists frequently augment these omissions with descriptions of the 'Yicha ng' clone. Apomixis occurs in Malus, including M. hupehensis, and is strong ly associated with elevated ploidy levels. Simple sequence repeats (SSRs) w ere used to characterize 65 accessions of M. hupehensis. To check for polyp loidy, 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 k nown nor suspected that the U.S. National Plant Germplasm System held many duplicate accessions of the 'Yichang' clone prior to their molecular charac terization. Germplasm conservation decisions for Malus species can benefit from an increased knowledge of the genetic variation or lack thereof in nat uralized populations and ex situ collections.