Characterization of the Field Fludioxonil Resistance and Its Molecular Basis in Botrytis cinerea from Shanghai Province in China

Abstract

Botrytis cinerea is a destructive necrotrophic pathogen that can infect many plant species. The control of gray mold mainly relies on the application of fungicides, and the fungicide fludioxonil is widely used in China. However, the field fungicide resistance of B. cinerea to this compound is largely unknown. In this study, B. cinerea isolates were collected from different districts of Shanghai province in 2015–2017, and their sensitivity to fludioxonil was determined. A total of 65 out of 187 field isolates (34.76%) were found to be resistant to fludioxonil, with 36 (19.25%) showing high resistance and 29 (15.51%) showing moderate resistance. Most of these resistant isolates also showed resistance to iprodione, and some developed resistance to fungicides of other modes of action. AtrB gene expression, an indicator of MDR1 and MDR1h phenotypes, was not dramatically increased in the tested resistant isolates. Biological characteristics and osmotic sensitivity investigations showed that the fitness of resistant isolates was lower than that of sensitive ones. To investigate the molecular resistance mechanisms of B. cinerea to fludioxonil, the Bos1 amino acid sequences were compared between resistant and sensitive isolates. Resistant isolates revealed either no amino acid variations or the mutations I365S, I365N, Q369P/N373S, and N373S.

Emergence of Fungicide Sensitivity in Leptosphaeria maculans Isolates Collected from the Czech Republic to DMI Fungicides

“…In vitro fungicide sensitivity studies are used to determine changes in the sensitivity of fungal isolates to a particular active ingredient over time. Testing is typically carried out using mycelial growth assays where the growth of isolates on fungicide amended medium is compared to the growth on nonamended medium [42][43][44]. This method, though, is usually cumbersome and time-consuming [45].…”

Activity of the Novel Fungicide SYP-34773 against Plant Pathogens and Its Mode of Action on Phytophthora infestans

“…For most pathogens, fresh mycelial plugs (5 mm in diameter) were inoculated in the center of solid media in Petri dishes (9 cm in diameter), with three replicates for each treatment. The plates were incubated at the appropriate temperatures in darkness until the colonies on the control media were approximately 7 cm in diameter, and the colony diameters were measured in two vertical dimensions . The inhibition ratios were calculated by comparing the colony diameters of the treatment and control groups.…”

“…The plates were incubated at the appropriate temperatures in darkness until the colonies on the control media were approximately 7 cm in diameter, and the colony diameters were measured in two vertical dimensions. 16 The inhibition ratios were calculated by comparing the colony diameters of the treatment and control groups. For S. reilianum and U. nuda, teliospores (10 mg) were added in 200 mL of the modified Richard's liquid medium (1 L of medium containing 10 g of KNO 3 , 5 g of KH 2 PO 4 , 2.5 g of MgSO 4 , 0.0333 g of FeCl 3 •6H 2 O, and 30 g of glucose) and mixed well, before which the surface sterilization has been conducted using a solution containing 0.25% KMnO 4 (25 min) and subsequently another solution containing 0.05 mol/L HCl (6 h).…”

Synthesis and bioactivity evaluation of 5‐trifluoromethyl‐1H‐pyrazole‐4‐carboxamide derivatives as potential anticancer and antifungal agents

“…More than 20 succinate dehydrogenase inhibitors (SDHIs) have been marketed since 1969 [16]; most of these contain pyrazole carboxamide skeletons [17]. However, long‐term and extensive application of SDHI fungicides has resulted in the development of resistance in pathogenic fungi, including Alternaria solani [18], Botrytis cinerea [19], Alternaria alternata [20], and Sclerotinia sclerotiorum [21]. Therefore, new fungicides with novel structures and excellent performances need to be developed.…”