Abstract
Reducing duplication in ex-situ collections is complicated and requires good quality genetic markers. This study was conducted to assess the value of endosperm proteins and SSRs for validation of potential duplicates and monitoring intra-accession variability. Fifty durum wheat (Triticum turgidum ssp. durum) accessions grouped in 23 potential duplicates, and previously characterised for 30 agro-morphological traits, were analysed for gliadin and high molecular weight glutenin (HMWG) subunit alleles, total protein, and 24 SSRs, covering a wide genome area. Similarity and dissimilarity matrices were generated based on protein and SSRs alleles. For heterogeneous accessions at gliadins the percent pattern homology (PH) between gliadin patterns and the Nei’s coefficient of genetic identity (I) were computed. Eighteen duplicates identical for proteins showed none or less than 3 unshared SSRs alleles. For heterogeneous accessions PH and I values lower than 80 identified clearly off-types with more than 3 SSRs unshared. Only those biotypes differing in no more than one protein-coding locus were confirmed with SSRs. A good concordance among proteins, morphological traits, and SSR were detected. However, the discrepancy in similarity detected in some cases showed that it is advisable to evaluate redundancy through distinct approaches. The analysis in proteins together with SSRs data are very useful to identify duplicates, biotypes, close related genotypes, and contaminations.
Highlights
In a broader sense, genebank duplication can be defined as accessions derived from the same original population, having alleles in common
We identified 106 potential duplicates of durum wheat accessions maintained at the National Plant Genetic Resources Centre (Spain) using passport data, 30 agro-morphological characters and gliadin banding patterns (Ruiz and Aguiriano, 2004)
All the gt. 1 identical for gliadins showed no differences in high molecular weight glutenin (HMWG) subunits and total protein, except for Berberisco and Recion duplicates
Summary
Genebank duplication can be defined as accessions derived from the same original population, having alleles in common. Historical duplicate accessions, may diversify from the primary sample in genetic composition during maintenance in ex-situ collections (Hintum and Knüpffer, 1995). For these reasons duplicate entries would be expected to be different from each other and from their common original accession, and form a genetically homogeneous group (Lund et al, 2003). The amount of genetic diversity acceptable between duplicate entries is still not well-defined. Reducing duplication is more complicated than generally assumed and requires good quality genetic markers to estimate genetic similarities. Cost, and reproducibility determine their utility for genebank management
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