Measuring resistance in durum wheat-Zymoseptoria tritici interaction using aggressiveness quantitative traits

Phenotyping for quantitative resistance to Septoria tritici blotch (STB), one of the most economically devastating diseases durum wheat (Triticum Desf.) in North African region, is a limiting factor breeding progress. Here we tested main phenotypic markers aggressiveness affecting host damage and pathogen reproduction reported earlier studies measuring differences resistance. A collection 11 Tunisian genotypes varying was inoculated by highly aggressive virulent isolate Zymoseptoria replicated field controlled experiments, conducted 2017-2018 at experimental station Regional Field Crops Research Center Beja Tunisia. The severity infection caused Z. isolate, including percentage leaf area covered chlorotic lesions (PLACCL), necrosis (PLACN), pycnidia (PLACP) as well latent period (LP) density (PYCdens) were assessed visually quantified. results showed that there significant all traits on positive correlations obtained between PLACN, PLACP PYCdens. Similarly, negative correlation LP these last traits. found more reliable trait discriminate different classes resistance, consistent with remaining These data suggest using both necrotic (PLACN) bearing PYCdens can improve selection STB