First Report of Brown Rot Caused by Monilinia polystroma on Quince in Italy

Abstract

HomePlant DiseaseVol. 107, No. 1First Report of Brown Rot Caused by Monilinia polystroma on Quince in Italy PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Brown Rot Caused by Monilinia polystroma on Quince in ItalyU. Spitaler, S. Oettl, and E. DeltedescoU. Spitaler†Corresponding author: U. Spitaler; E-mail Address: urban.spitaler@laimburg.ithttps://orcid.org/0000-0003-0492-6129Institute for Plant Health, Laimburg Research Centre, Auer (Ora) 39040, South Tyrol, ItalySearch for more papers by this author, S. OettlInstitute for Plant Health, Laimburg Research Centre, Auer (Ora) 39040, South Tyrol, ItalySearch for more papers by this author, and E. Deltedescohttps://orcid.org/0000-0002-0697-3642Institute for Plant Health, Laimburg Research Centre, Auer (Ora) 39040, South Tyrol, ItalySearch for more papers by this authorAffiliationsAuthors and Affiliations U. Spitaler † S. Oettl E. Deltedesco Institute for Plant Health, Laimburg Research Centre, Auer (Ora) 39040, South Tyrol, Italy Published Online:24 Oct 2022https://doi.org/10.1094/PDIS-06-22-1442-PDNAboutSectionsPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Brown rot, caused by Monilinia spp., is an important disease of stone and pome fruits in Italy. The main pathogens are Monilinia laxa, M. fructigena, and M. fructicola. In 2009, a new species, Monilinia polystroma (G. Leeuwen) L. M. Kohn, was found in Europe (Petróczy and Palkovics 2009). The first reports of M. polystroma on pome fruit for Italy were on pear in 2013 (Martini et al. 2015) and on apple in 2021 (Rosati et al. 2021). During a survey in Italy, it was observed that quince (Cydonia oblonga Mill.), a plant of the Rosaceae family and a pome fruit, was frequently affected by brown rot. To determine the pathogen, single spore isolates were obtained from symptomatic fruits of a quince plant in Kaltern/Caldaro (South Tyrol, Italy) in September 2021. On the selected tree, one-third of the fruit showed brown rot symptoms. The isolates showed morphological characteristics compared to M. polystroma on potato dextrose agar (PDA) at 22°C and a photoperiod of 16 h (Vasić et al. 2016). The colonies were grayish brown with slightly undulate margins. The colony reverse developed black stromatal plates in concentric rings within 14 days post inoculation (dpi). DNA was extracted from mycelium and the internal transcribed spacer (ITS) region using ITS6/ITS4 primers (White et al. 1990) as well as a genomic sequence with unknown function using the primers UniMon_Forw/UniMon_Rev (Petróczy et al. 2012), were amplified and sequenced. MegaBLAST analysis revealed 100% identity with M. polystroma (accession nos. NR_154198 and JN128836, respectively). Sequences were deposited in NCBI GenBank under the accession numbers ON646524 and ON806527. To confirm pathogenicity, 10 mature pear quinces from organic production were surface sterilized with 75% ethanol. Mycelial plugs (2 mm) were dislodged from an 8-day-old colony and inserted into a 3 mm hole in the quince. Ten fruits inoculated with sterile PDA plugs were used as a control. Quinces were incubated in a plastic box at 22°C, 16 h photoperiod, and 100% relative humidity. Brown rot lesions developed within 1 day. Additionally, inoculation with spores was performed. One-celled, limoniform, hyaline conidia, measuring 11.7 to 19.4 × 8.8 to 13.1 μm, were obtained from mycelium-inoculated quinces 9 dpi. Ten quinces were wounded with a sterile needle and inoculated with 20 μl conidial suspension (1.1 × 104 spores/ml). Ten quinces inoculated with sterile water were used as a control. After 4 days, brown rot lesions developed on all spore-inoculated fruits. Mean lesion radius (±SD) was 2.5 (±0.8) mm 4 dpi, 25.4 (±1.5) mm 7 dpi, and 45.0 (±4.4) mm 11 dpi. One month after inoculation, all quinces were completely covered by the lesion, while all control fruits remained symptomless. To confirm identity, the fungus was isolated from four spore-inoculated fruit. The isolates showed the same morphological and molecular features as the original isolate. Sequences were deposited in GenBank under the accession numbers ON646525 to ON646528 and ON806528 to ON806531. Although the presence of M. polystroma has been documented for Italy, this is the first report of this species on Italian quinces. The high number of infected fruits found in this study suggests a broad impact of M. polystroma on Italian quince cultivation. Due to the widespread cultivation of quinces, additional knowledge of the occurring pathogens will help to assign brown rot symptoms to M. polystroma and to improve targeted control strategies.The author(s) declare no conflict of interest.