Genetic analysis of accessions in a pear germplasm bank

Abstract

Genetic diversity of germplasm collections is the base of breeding programs and it is essential to the raising of new genetic combinations aimed at the development of new cultivars. In Brazil, the pear germplasm collection is maintained in orchards by the EPAGRI-EE Caçador. The aim of this work was to analyze the genetic diversity of an initial sample of 46 accessions of this collection, by Random Amplified Polymorphic DNA (RAPD). European (Pyrus communis), Asian (P. pyrifolia and P. ussuriensis) and hybrid cultivars were used. From 160 randomic primers, 11 primers, yielding 87 reproducible and polymorphic markers, were chosen and used for similarity analysis. The cluster analysis resulted in a dendrogram that showed, with few exceptions, European, Asian and hybrid cultivars as distinct groups. By using these markers, the Chinese and Japanese cultivars could be discriminated. The study illustrates how genetic information can be valuable to the organization of germplasm collections. Accessions named differently as 'William's' and 'Bartlett' showed 100% of genetic similarity and probably correspond to the European pear cultivar 'Bon Chrétien Williams' (synonym: 'Williams - Bartlett de Boston'). On the other hand, two accessions identified with the same name, 'Óstia', did not show genetic identity and are, therefore, distinct accessions. This study is being extended to several other accessions of the collection and completed with the analysis of DNA hypervariable regions (microsatellites).