Genetic structure of a Ribes genetic resource collection: inter- and intra- specific diversity revealed by chloroplast DNA simple sequence repeats (cpSSRs)

Currants and gooseberries (Ribes sp.) are important berry crops with high nutritional value, and the efficient development of new cultivars depends on the characterisation of Ribes genetic resources and successful inclusion into breeding materials. Ribes breeding programs are characterised by the extensive use of interspecific crosses to introduce required traits. In some cases, this makes it challenging to identify the genomic contribution of particular species to cultivars, thus limiting the understanding of the heredity of these traits. To clarify these issues, the present study aimed to evaluate the applicability of selected chloroplast SSR molecular markers to analyse germplasm consisting of genotypes developed through complicated multistage crosses among different Ribes species. This provides information on Ribes germplasm species composition and blackcurrant collection species structure, thus assessing the applicability and utility of the blackcurrant collection in breeding. Fifty cpSSR molecular markers previously developed for plants were assessed, and a set of 19 markers was selected for further analysis of a Ribes genetic resource collection. A set of 145 Ribes genotypes was analysed using the selected chloroplast markers: blackcurrants (R. nigrum L.), redcurrant (R. rubrum L.), European gooseberry (R. uva-crispa L.), mountain currant (R. alpinum L.), golden currant (R. aureum Pursh), R. americanum Mill., jostaberry (R. × nidigrolaria Rud.Bauer & A.Bauer), R. ussuriense Jancz., R. komarovii Pojark., R. sanguineum Pursh., R. latifolium Jancz., R. fasciculatum var. chinense Maxim., R. fragrans Pall., R. laxiflorum Pursh. and their interspecific hybrids. The cpSSR markers are suitable for differentiating Ribes species and thus are suitable for analysing germplasm collections, showing relationships regarding pedigree. The markers are good at showing the structure of a germplasm collection. However, in the case of complex interspecies crossings, identifying a specific percentage of a species within an accession cannot be guaranteed.