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Updating DUS resistance tests according to pests’ evolution

Pests are continuously evolving, certainly due to selection pressure of monogenic resistance genes, climate change and other constrains, and sometimes new strains rapidly spread with seeds. Breeding companies respond to this evolution by proposing varieties with new resistance traits and therefore DUS system has to develop resistance tests for these new resistances. Following discussion between examination offices and seed companies and the DRT ISF work, ToBRFV and Aphis gossypii were identified as needing test definition or test updating for vegetables. GAFL is the pillar partner of this project for improvement of the resistance test  to Aphis gossypii in melon.  Aphis gossypii is a DUS characteristic known to not include the evolution of biotypes described by Mistral et al 2021 and some symptoms observed in field. The objectives are :

• Identify predominant clones in South Europe
• Establish a table of differentials for the Aphis gossypii biotypes
• Test alternative protocols for evaluation of resistance: leaf-curling or Vat gene marker