Аннотация:In 2018–2021 tubers with cavities filled with brownish-orange mycelium were found in different potato facilities of the Moscow region with frequency up to 3%. Three tubers were collected for analysis: two in 2018 and one in 2021. Axenic cultures (18MPT92, 18MPT135, and 21MPT11/1) were isolated from those tubers. After 10–12 days at 25 °C in a 16/8 light/dark cycle on potato-glucose agar (PGA), all strains formed orange 40–50 mm colonies. Microscopic observations revealed narrowly flask-shaped phialides and oval, pale reddish conidia 3.5–5.5 × 2.5–3.5 μm, ratio length/width = 1.4–1.6. Those morphological characteristics corresponded to Acrostalagmus luteoalbus (Link) Zare, W. Gams & Schroers (Zare et al. 2004). For identification, portions of ITS (primers ITS5/ITS4) and 28 S rDNA (NL1/NL4) regions were sequenced (Kutuzova et al. 2017). TheITS sequences of the three strains (GenBank accessions OM189521, OM189522, OM189523) were 100% identical to the sequence of A. luteoalbus strain CBS388.65 (MH858627). The sequences of 28 S rDNA of the isolates 21MPT11/1 (OM189526), 18MPT92 (OM189524), and 18MPT135 (OM189525) were 100% identical to sequences of the A. luteoalbus strains CBS331.52 (LR025793), CBS325.61 (MH869638), and CBS388.65 (MH870266),respectively. To determine pathogenicity, 20 μl of a spore suspension (1x105 spores/ ml) was applied to inoculate 7 potato slices and 7 whole intact potato tubers, which were then incubated in humid chambers at 25 °C in a 16/8 light/dark cycle. As a control, tuber slices and whole tubers were inoculated with a drop of sterile water. Control slices and tubers after 10 days of incubation were symptomless. After 7 days mycelium of all tested strains developed on the potato slices, followed after 10 days by the orange sporulation. Allthree strains could not infect whole intact tubers. Spores from several slices were re-isolated and colonies were identical to the parental strains. To our knowledge, this is thefirst report of potato tuber disease caused by A. luteoalbus.
