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Open AccessArticle
Context-Dependent Fitness Trade-Offs in Penicillium expansum Isolates Resistant to Multiple Postharvest Fungicides
by
Jonathan T. Puglisi
Jonathan T. Puglisi
and
Achour Amiri
Achour Amiri *
Department of Plant Pathology, Tree Fruit Research and Extension Center, Washington State University, 1100 N. Western Ave., Wenatchee, WA 98801, USA
*
Author to whom correspondence should be addressed.
Microorganisms 2025, 13(8), 1846; https://doi.org/10.3390/microorganisms13081846 (registering DOI)
Submission received: 20 June 2025
/
Revised: 30 July 2025
/
Accepted: 5 August 2025
/
Published: 7 August 2025
Abstract
Blue mold of pome fruit, caused by Penicillium expansum, is controlled through postharvest applications of thiabendazole (TBZ), pyrimethanil (PYR), and fludioxonil (FDL). However, multi-fungicide-resistant isolates have emerged in the U.S. Pacific Northwest and their impact on decay control in long-term storage is unknown. This study evaluated the fitness of P. expansum isolates sensitive to all three postharvest fungicides (wild-types) and those resistant to TBZ (single-resistant), TBZ and PYR, or PYR and FDL (dual-resistant), and triple-resistant to the three fungicides. On nutrient-poor media, resistant isolates showed reduced conidial germination, whereas no significant differences were observed in germination, mycelial growth, or sporulation between phenotypes on nutrient-rich media at 1.5 and 20 °C. Regardless of their sensitivity phenotype, FDL-resistant isolates showed increased sensitivity to osmotic and oxidative stresses. Pathogenicity and virulence were not affected by the sensitivity phenotype on apples after six months of storage at 1.5 °C. Analysis of cumulative fitness changes indicated fitness loss under low-temperature in vitro and increased fitness under fungicide selection pressure on fruit in most resistant phenotypes. Gene expression analysis showed differential regulation of fitness-related genes, with most being up-regulated by TBZ. Overall, the results suggest that resistance in P. expansum may carry context-dependent fitness penalties, especially under high-stress conditions.
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MDPI and ACS Style
Puglisi, J.T.; Amiri, A.
Context-Dependent Fitness Trade-Offs in Penicillium expansum Isolates Resistant to Multiple Postharvest Fungicides. Microorganisms 2025, 13, 1846.
https://doi.org/10.3390/microorganisms13081846
AMA Style
Puglisi JT, Amiri A.
Context-Dependent Fitness Trade-Offs in Penicillium expansum Isolates Resistant to Multiple Postharvest Fungicides. Microorganisms. 2025; 13(8):1846.
https://doi.org/10.3390/microorganisms13081846
Chicago/Turabian Style
Puglisi, Jonathan T., and Achour Amiri.
2025. "Context-Dependent Fitness Trade-Offs in Penicillium expansum Isolates Resistant to Multiple Postharvest Fungicides" Microorganisms 13, no. 8: 1846.
https://doi.org/10.3390/microorganisms13081846
APA Style
Puglisi, J. T., & Amiri, A.
(2025). Context-Dependent Fitness Trade-Offs in Penicillium expansum Isolates Resistant to Multiple Postharvest Fungicides. Microorganisms, 13(8), 1846.
https://doi.org/10.3390/microorganisms13081846
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