o:34970 Oxalic acid production and aggressiveness of Sclerotinia spp. isolates en Sclerotinia sclerotiorum and Sclerotinia minor are two necrotrophic fungal species that cause white mould disease in many crops. Oxalic acid, secreted by Sclerotinia species, is recognized to be a major virulence factor involved in the induction of cell death in host plants during infection establishment. The aim of this study was to determine relationship between oxalic acid production in S. sclerotiorum and S. minor isolates and their aggressiveness toward lettuce as a model plant. Ten isolates of S. sclerotiorum and ten isolates of S. minor, derived from diseased lettuce plants, were tested simultaneously for their ability to produce oxalic acid and to cause necrosis in an inoculation experiment. Oxalic acid production was measured spectrophotometrically in a liquid medium, while the inoculation test was conducted on lettuce leaf discs. As a control, sterile liquid medium and PDA (Potato Dextrose Agar) plugs were used, respectively. Higher production of oxalic acid was recorded in S. minor isolates, ranging from 19 to 96.3 μg oxalic acid mg−1 dry mycelium weight, while S. sclerotiorum isolates produced significantly lower amount of oxalic acid (21.9 to 29.9 μg oxalic acid mg−1 dry wt). All Sclerotinia spp. isolates were able to establish infection in inoculated leaf disks. On average, the diameter of necrosis was slightly higher for S. minor isolates (11.7 mm), although the difference between species was not statistically significant. Correlation between aggressiveness and oxalic acid production among Sclerotinia spp. isolates was not recorded, suggesting the contribution of some other factors to the necrosis establishment and spreading. virulence factor, lettuce, white mould disease 1552100 978-86-912591-7-4 2024-10-23T06:39:44.591Z 44 yes 46 Milica Mihajlović Institute of Pesticides and Environmental Protection, Belgrade, Serbia Maja Živanović Institute of Pesticides and Environmental Protection, Belgrade, Serbia person Jovana Hrustić Institute of Pesticides and Environmental Protection, Belgrade, Serbia person Aleksandra Jovanović University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia doktor tehnoloških nauka person 0000-0001-5394-0125 Brankica Pešić Institute of Pesticides and Environmental Protection, Belgrade, Serbia person application/pdf 1578424 https://phaidrabg.bg.ac.rs/o:34970 no yes 19 70 92000004 11A29 11A2910 Oxalic acid production and aggressiveness of Sclerotinia spp. isolates 111 Book of Abstracts 5th International Conference on Plant Biology (24th SPPS Meeting) 2024