Fusarium isolates from Belgium causing wilt in lettuce show genetic and pathogenic diversity

• DOI: 10.1111/ppa.13668
• Publication Date: 2022-11-04T07:39:09Z
• Authors: Jolien Claerbout; Kris Van Poucke; Hanna Mestdagh; Ilse Delaere; Isabel Vandevelde; Sofie Venneman; An Decombel; Peter Bleyaert; Jenny Neukermans; Nicole Viaene; Kurt Heungens; Monica Höfte
• Keywords: Wilting

Abstract Fusarium oxysporum f. sp. lactucae race 4 causes vascular necrosis and wilting of lettuce. First observed in Belgium 2015, the lack disease resistance commercial cultivars allowed this pathogen to spread nearly entire Belgian production area within years. Different levels development were different greenhouses. To help explain variation, we collected 78 isolates characterized them both physiologically genetically. Molecular identification indicated that 91% belonged 4, while 6% 1, which was not previously reported Belgium. Pathogenicity assays using differential confirmed molecular assignment selected isolates. Cultivar Patriot identified as a suitable new cultivar 4. Race more aggressive than 1 at 24°C, but only when chlamydospore inoculum instead root dip assay containing microconidia. Variation pathogenicity aggressiveness races may differences Based on genotyping‐by‐sequencing (GBS), highly similar reference curvatum , F . tulipae rhois phylogenetically separated from based GBS data, multilocus sequence data. Within data differentiated two rather homogeneous groups, suggesting least introductions. However, groups did differ aggressiveness.