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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #311094
Title: Genetic diversity of medlar (Mespilus germanica) germplasm using microsatellite markers

Author
item SCHAEFER, KACEY - Oregon State University
item Nyberg, April
item Postman, Joseph
item Bassil, Nahla

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2014
Publication Date: 9/20/2015
Citation: Schaefer, K., Nyberg, A.M., Postman, J.D., Bassil, N.V. 2015. Genetic diversity of medlar (Mespilus germanica) germplasm using microsatellite markers. Acta Horticulturae. 1094:47-56.

Interpretive Summary: Medlar is a pome fruit related to pear and hawthorn that has been cultivated for many centuries for its edible fruit. It was also an important medicinal plant in the Middle Ages. The center of origin for wild medlar is the Caucasus Mountain region east of the Black Sea. A medlar collection at the USDA National Clonal Germplasm Repository includes 60 seed and plant accessions with origins in 10 countries. Several ancient cultivars are very similar and may be the same variety with different names. Twenty-one DNA markers that have been used to fingerprint apples and pears were tested on medlar and nine apple markers were useful. This study reports on the use of five of these apple markers to compare 42 medlars and close relatives. Seven large fruited varieties from five different countries of origin were genetically indistinguishable from the ‘Monstreuse d’Evreinoff’ medlar. Four different medlars from western Oregon sources also had DNA fingerprints that were identical to each other. The relationships determined in this study document the diverse genetic backgrounds represented in the NCGR medlar collection. These results also will permit the removal of unnecessary duplication and improve the efficient management of this collection.

Technical Abstract: The medlar (Mespilus germanica) is a pome fruit related to pear (Pyrus sp.) and hawthorn (Crataegus sp.) that has been cultivated for many centuries for its edible fruit. It was also an important medicinal plant in the Middle Ages. The center of origin for Mespilus is the Trans-Caucasus region and traditional uses for the fruit extend through the Middle East, Central Asia and western Europe. The Mespilus collection at the USDA National Clonal Germplasm Repository (NCGR) at Corvallis, Oregon, USA, includes 60 seed and plant accessions with origins in 10 countries. Several ancient cultivars with different names and sources have indistinguishable phenotypes and synonymy has long been suspected. Twenty-one simple sequence repeat (SSR) markers from apple and two from pear were tested for polymorphism in eleven medlar accessions. Nine apple SSRs were polymorphic in medlar. Five easy- to-score SSRs from apple were used to genotype 41 clones of M germanica and one accession of the intergeneric hybrid species M. canescens growing at the NCGR. Seven very large fruited clones with five different countries of origin were genetically indistinguishable from ‘Monstreuse d’Evreinoff’. Four clones from western Oregon sources with similar phenotypes also produced identical SSR profiles. Two other pairs of synonyms were also documented. One of the five SSRs (NZ05g8) distinguished ‘Marron’ and ‘Macrocarpa’ from the ancient English cultivar ‘Nottingham’. Flow cytometry confirmed M. canescens as triploid and showed all M. germanica accessions to be diploid. The relationships determined in this study document the diverse genetic backgrounds represented in the NCGR medlar collection. These results also will permit the removal of unnecessary duplication and improve the efficient management of this collection.