S14 - Session P5 - Validation of two internationally standardized detection methods (Peronospora and Phoma valerianellae) on corn salad seeds for ISHI-Veg

Authors: Geoffrey Orgeur *, Juliette Desliles, Valérie Grimault

Several detection methods for Peronospora ( Pv ) and Phoma valerianellae ( P hv ) exist in the seed industry. Some are based on a grow-out (germination on substrate and observation of symptoms for Pv or Phv ) while others on a seed wash with observation of oospores ( Pv ) or observation of suspect colonies on media or blotters ( Phv ). Following a comparison of different methods (grow-out for Pv and detection on media for Phv ) in use in 2018, standardized ISHI-Veg grow-out methods for the detection of Pv and Phv in corn salad seed were developed. After va rious technical comparison of modalities for each protocols (watering, sowing, environmental conditions, characterization of typical infected plantlet for Phv and selectivity of the media, characterization of the typical suspect colonies, pathogenicity test and PCR confirmation for Phv ) , description and analys i s of the performance criteria (analytical sensitivity and specificity, selectivity and repeatability) were carried out in order to organize an international validation comparative test. Different seed companies and institutes' laboratories were volunteers to participate to these international validations comparative test ongoing in 2021 -2022 . Methodologies, comparison, results of the international comparative test and standardized detection protocols published will be presented.