Identification of Duplicates in Mulberry Germplasm Using Morphological Descriptors and SSR Markers

Abstract

Germplasm collections invariably contain duplicate accessions, both within and between genebanks. These redundancies are a burden for curators because they do not contribute to the diversity in the collection, but do require genebank budget for maintenance. Thus, both from a genetic and economic point of view, identification and elimination of redundancies should be an important genebank objective. In field gene banks, duplicate accessions are widespread and their identification is required to facilitate germplasm administration and lower the maintenance costs. The goal of this study was to identify the duplicates in mulberry germplasm that has been morphologically and agronomically evaluated. Until now the identification of duplicate accessions had to rely on comparison of morphological characters which are subject to environmental variation. However, it is possible to make routine use of molecular markers based on genomic DNA for the identification of duplicate accessions of vegetatively propagated species. In the present study, among the mulberry germplasm 312 accessions were characterized using 17 qualitative morphological descriptors and identifiied 84 suspected duplicates using multivariate cluster analysis. Further, the suspected duplicates were screened using 12 SSR markers and scored the polymorphic alleles using binary format. The data matrix was subjected to multivariate cluster analysis and 14 mulberry accessions were confirmed as true duplicates. The identification of redundant accessions enables curators to concentrate their efforts on the characterization, evaluation, and regeneration of distinct genetic material. The molecular markers aids in giving priorities for the evaluation and regeneration of unique genetic materials in field genebank.