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Pine Blister Rust Resistance Screening in Ribes Germplasm

Hummer, Kim E., Picton, Deric D.
Acta horticulturae 2002 no.585 pp. 287
Ribes, currants, gooseberries, genetic variation, disease resistance, rust diseases, Cronartium ribicola, Oregon
A preliminary study at the National Clonal Germplasm Repository in Corvallis, Oregon, determined that 110 field-grown Ribes L. genotypes were resistant to natural infection from white pine blister rust (Cronartium ribicola C. J. Fischer). Uredinia did not form under conditions of natural infection on these black currant (R. nigrum L.), red currant (R. rubrum L., R. sativum L.) or gooseberry (R. uva-crispa L., R. oxyacanthoides L.) genotypes for 3 to 5 years. The objective of this study was to determine if uredia would develop on these resistant genotypes after artificial inoculation. Ribes nigrum cv. Ben Alder was chosen as a susceptible control. In August 2000, uredinial spores were gathered from infected black currants leaves in the Corvallis field planting. An agar-water suspension (30,000 spores ml-1) was prepared and applied to leaves of four branches of intact plants for each clone. Three weeks after inoculation, 68 of the tested clones developed infection. The abaxial leaf surfaces of the blackcurrants 'Ben Alder' and 'Pilot Alexandr Mamkin' and R. x nidigrolaria Bauer cv. Jostiki, were covered with uredinia. Fewer uredinia developed on R. x nidigrolaria Bauer cv. Josta, 26 black, 11 red, 5 white currants and 12 gooseberries. No uredinia developed on 42 clones, including 12 black, 5 red, 1 white currant, or 24 gooseberries. Blackcurrant cultivars with the Cr gene for white pine blister rust immunity, i.e., Consort, Coronet, Crusader, or Titania, remained uninfected. The broad range of species and geographical origins of the highly resistant, uninfected clones suggest that several additional genetic mechanisms for rust resistance may exist in Ribes. Further studies will seek to identify additional rust-immune genotypes.