First Report of Talaromyces wortmannii Causing Peach Fruit Rot at Postharvest Stage in China

Peach (Amygdalus persica) is a widely cultivated fruit crop in China, and postharvest diseases severely threaten the fruit industry and quality. Colletotrichum spp. have been reported as the main causal agent of postharvest diseases on peach fruits (Tan et al. 2022). In October 2025, postharvest rot was observed during room-temperature storage in Shijiazhuang City, Hebei Province. Disease incidence was 6% (9 of 150 fruits) of four cartons. Initially, the diseased tissue surface appeared as a pale brownish, water-soaked, circular discoloration with softening flesh and distinct boundaries. Approximately 1 to 2 days later, a blue-green, powdery mold layer was found at the center of the white mold layer. The rot area rapidly expanded on the surface and deepen to the flesh with a funnel-shape. A small amount of mold was aseptically picked with a sterile needle and transferred into a centrifuge tube containing sterile water. After thorough resuspension, the suspension was subjected to a series of gradient dilutions. An aliquot of the diluted suspension was then spread onto potato dextrose agar (PDA) plates and incubation at 25C for 5 days. Four isolates with similar morphological characteristics were obtained, and one of them (named HBND) was selected for further morphological and molecular identification. On PDA, the colony appears as dark green, velvety mycelium with a centrally elevated and marginally depressed topography. Conidiophores (approximately 80-200 × 2-4 µm; n=50) are aggregated in clusters and are typically symmetrically biverticillate, bearing 1 or 2 tiers of branching and collectively forming a broom. Conidia are smooth-walled, hyaline, and oval, measuring 2.5-3.8 × 1.8-2.5 µm (n=50), and are arranged in long, densely packed chains. The genomic DNA of isolate (HBND) was extracted by CTAB protocol. The ribosomal DNA internal transcribed spacer (ITS) region and the ribosomal large subunit (LSU) were amplified and sequenced with primers ITS1/4, LR5/LROR respectively (Xu et al. 2010). Sequence alignment results showed that the ITS-rDNA and LSU sequences of the isolate (GenBank accession nos. PX672542 and PX716855) exhibited 100% and 99.8% identity with the reference sequences of T. wortmannii (GenBank accession nos. MZ573039 and MH870646), respectively. Based on morphological (Samson et al. 2011) and molecular characterization (ITS and LSU sequence comparisons), the peach fruit rot pathogen was identified as T. wortmannii (Stephen et al. 2017). To test pathogenicity, surface-sterilized peach fruits were wounded and then inoculated with a 10 µL drop of conidial suspension (1 × 10 4 spores/mL), with sterile water treatment serving as the control, and then incubated at 25C and 85% relative humidity. After 3 days, inoculated fruit showed symptoms similar to those observed under room-temperature storage (pale brown, water-soaked lesions), whereas all controls remained asymptomatic. T. wortmannii was reisolated from the diseased tissue and identified by morphological and molecular analyses, fulfilling Koch’s postulates. To our knowledge, this is the first report T. wortmannii as a pathogen causing postharvest peach fruit rot disease in China. This finding provides a basis for the development of effective prevention and management strategies for postharvest peach diseases.