Exploring Potential Mechanisms of Fludioxonil Resistance in Fusarium oxysporum f. sp. melonis

Abstract

Melon Fusarium wilt (MFW), which is caused by Fusarium oxysporum f. sp. melonis (FOM), is a soil-borne disease that commonly impacts melon cultivation worldwide. In the absence of any disease-resistant melon cultivars, the control of MFW relies heavily on the application of chemical fungicides. Fludioxonil, a phenylpyrrole fungicide, has been shown to have broad-spectrum activity against many crop pathogens. Sensitivity analysis experiments suggest that fludioxonil has a strong inhibitory effect on the mycelial growth of FOM isolates. Five fludioxonil-resistant FOM mutants were successfully generated by repeated exposure to fludioxonil under laboratory conditions. Although the mutants exhibited significantly reduced mycelial growth in the presence of the fungicide, there initially appeared to be little fitness cost, with no significant difference (p < 0.05) in the growth rates of the mutants and wild-type isolates. However, further investigation revealed that the sporulation of the fludioxonil-resistant mutants was affected, and mutants exhibited significantly (p < 0.05) reduced growth rates in response to KCl, NaCl, glucose, and mannitol. Meanwhile, molecular analysis of the mutants strongly suggested that the observed fludioxonil resistance was related to changes in the sequence and expression of the FoOs1 gene. In addition, the current study found no evidence of cross-resistance between fludioxonil and any of the other fungicides tested. These results indicate that fludioxonil has great potential as an alternative method of control for FOM in melon crops.

A Conservative Mutant Version of the Mrr1 Transcription Factor Correlates with Reduced Sensitivity to Fludioxonil in Botrytis cinerea

“…The low frequency of these isolates is consistent with worldwide reports and correlates with the high efficacy of fludioxonil in table grape phytosanitary programs [17]. However, compared to isolates from the United States and China, Chilean isolates with low fludioxonil sensitivity exhibit little to no fitness cost [37,[41][42][43].…”

Resistance Risk and Molecular Mechanism of Tomato Wilt Pathogen Fusarium oxysporum f. sp. lycopersici to Pyraclostrobin

“…Currently, extensive research has been conducted on the resistance of F. oxysporum to well-known mainstream fungicides such as fludioxonil (phenylpyrrole), phenamacril (cyanoacrylate), tebuconazole (sterol biosynthesis inhibitor fungicides), and benomyl (benzimidazole fungicide) . However, there is a lack of research on the resistance of F.…”

Characterization and In Vitro Fungicide Sensitivity of Two Fusarium spp. Associated with Stem Rot of Dragon Fruit in Guizhou, China

“…However, many studies have reported an increase in the fungicide-resistant strains of several types of pathogens [25]. Notably, the major plant pathogen F. oxysporum, which affects tomatoes, potatoes, dragon fruit, and other commercial crops, has demonstrated resistance to various fungicides, including difenoconazole and tebuconazole [26,27]. Understanding the sensitivity of pathogens to various fungicides and employing appropriate doses are critical for effective chemical control of the disease, as well as environmental protection.…”