Logarithmic Transformation is Essential for Statistical Analysis of Fungicide EC50 Values

Liang, Hongjie; Li, Jinli; Di, Ya-Li; Zhang, An-Sheng; Zhu, Fuxing

doi:10.1111/jph.12342

Cited by 29 publications

(13 citation statements)

References 25 publications

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“…The resistance factor (RF) of each resistant isolate was calculated as a ratio of the EC 50 to the mean EC 50 of all sensitive isolates collected in the years 1996 to 2012. All EC 50 values were log 10 -transformed prior to statistical analysis (Liang et al, 2015 ), statistical analysis was performed with IBM SPSS (Statistical Product and Service Solutions, version 24.0, Armonk, NY, USA). EC 50 values of populations were compared using Student's t -test with the significance threshold set at 5%; correlations between EC 50 values were determined with Spearman's rank order correlation with the significance threshold set at 1%.…”

Section: Methodsmentioning

confidence: 99%

Demethylase Inhibitor Fungicide Resistance in Pyrenophora teres f. sp. teres Associated with Target Site Modification and Inducible Overexpression of Cyp51

et al. 2016

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Pyrenophora teres f. sp. teres is the cause of net form of net blotch (NFNB), an economically important foliar disease in barley (Hordeum vulgare). Net and spot forms of net blotch are widely controlled using site-specific systemic fungicides. Although resistance to succinate dehydrogenase inhibitors and quinone outside inhibitors has been addressed before in net blotches, mechanisms controlling demethylation inhibitor resistance have not yet been reported at the molecular level. Here we report the isolation of strains of NFNB in Australia since 2013 resistant to a range of demethylase inhibitor fungicides. Cyp51A:KO103-A1, an allele with the mutation F489L, corresponding to the archetype F495I in Aspergillus fumigatus, was only present in resistant strains and was correlated with resistance factors to various demethylase inhibitors ranging from 1.1 for epoxiconazole to 31.7 for prochloraz. Structural in silico modeling of the sensitive and resistant CYP51A proteins docked with different demethylase inhibitor fungicides showed how the interaction of F489L within the heme cavity produced a localized constriction of the region adjacent to the docking site that is predicted to result in lower binding affinities. Resistant strains also displayed enhanced induced expression of the two Cyp51A paralogs and of Cyp51B genes. While Cyp51B was found to be constitutively expressed in the absence of fungicide, Cyp51A was only detected at extremely low levels. Under fungicide induction, expression of Cyp51B, Cyp51A2, and Cyp51A1 was shown to be 1.6-, 3,- and 5.3-fold higher, respectively in the resistant isolate compared to the wild type. These increased levels of expression were not supported by changes in the promoters of any of the three genes. The implications of these findings on demethylase inhibitor activity will require current net blotch management strategies to be reconsidered in order to avoid the development of further resistance and preserve the lifespan of fungicides in use.

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Section: Methodsmentioning

confidence: 99%

Demethylase Inhibitor Fungicide Resistance in Pyrenophora teres f. sp. teres Associated with Target Site Modification and Inducible Overexpression of Cyp51

et al. 2016

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“…Resistance factors (RF) were calculated as a ratio of the isolate EC 50 to the mean EC 50 of isolates collected 1996-2013. EC 50 values were log 10 -transformed (Liang et al 2015) prior to statistical analysis with SPSS Statistics 24 (IBM, Armonk, NY, USA), using Kruskal-Wallis H test & Dunnett's T3.…”

Section: Characterisation Of In Vitro Fungicide Sensitivity Phenotypesmentioning

confidence: 99%

Parallel evolution of multiple mechanisms for demethylase inhibitor fungicide resistance in the barley pathogenPyrenophora teresf. sp.maculata

Mair

Thomas

Dodhia

et al. 2019

Preprint

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The demethylase inhibitor (DMI) or group 3 fungicides are the most important class of compounds for the control both of plant and human fungal pathogens. The necrotrophic fungal pathogen Pyrenophora teres f. sp. maculata (Ptm), responsible for spot form of net blotch (SFNB), is currently the most significant disease of barley in Australia, and a disease of increasing concern worldwide. The main basis for management of SFNB is by fungicide application, and in Australia the DMIs predominate. Although reduced sensitivity to DMI fungicides has recently been described in the closely related pathogen P. teres f. sp. teres (Ptt), the mechanisms of DMI resistance have not thus far been described for Ptm. In this study, several different levels of sensitivity to DMI fungicides were identified in Western Australian strains of Ptm from 2016 onwards, and reduced sensitivity phenotypes were correlated with a number of distinct mutations in both the promoter region and coding sequence of the DMI target gene encoding cytochrome P450 sterol 14α-demethylase (Cyp51A). Five insertions elements of 134-base pairs in length were found at different positions within the upstream regulatory region of Cyp51A in both highly DMI-resistant (HR) and select moderately DMI-resistant (MR1) Ptm isolates. The five insertion elements had at least 95% sequence identity and were determined to be Solo-LTR (Long Terminal Repeat) elements, all deriving from Ty1/Copia-family LTR Retrotransposons. The 134-bp elements contained a predicted promoter sequence and several predicted transcription factor binding sites, and the presence of an insertion element was correlated with constitutive overexpression of Cyp51A. The substitution of phenylalanine by leucine at position 489 of the predicted amino acid sequence of CYP51A was found in both HR and select moderately DMI-resistant (MR2) Ptm isolates. The same F489L amino acid substitution has been previously reported in Western Australian strains of Ptt, where it has also been associated with reduced sensitivity to DMI fungicides. In Ptm, the F489L amino acid change was associated with either of three different single nucleotide polymorphisms in codon 489. This suggests that, in contrast to Ptt, in Ptm the F489L mutation has emerged as a result of three distinct mutational events. Moderately DMI-resistant isolates had one or the other of the F489L substitution or a promoter insertion mutation, whereas highly DMI-resistant isolates were found to have combinations of both mechanisms together. Therefore, multiple mechanisms acting both alone and in concert were found to contribute to the observed phenomena of DMI fungicide resistance in Ptm. Moreover, these mutations have apparently emerged repeatedly and independently in Western Australian Ptm populations, by a process of convergent or parallel evolution.

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“…The normality of the data was verified using the Shapiro-Wilk W test (Shapiro and Wilk 1965). The data were log-transformed to improve normality (Liang et al 2015). Two-way analysis of variance (ANOVA) was used to test the effect of treatment and the concentration using Statistica 11 (Statsoft).…”

Section: Discussionmentioning

confidence: 99%

Toxicity of Different Zinc Oxide Nanomaterials at 3 Trophic Levels: Implications for Development of Low‐Toxicity Antifouling Agents

Dobretsov

Sathe

Bora

et al. 2020

Enviro Toxic and Chemistry

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Because zinc oxide (ZnO) nanomaterials are used in antifouling and antibacterial solutions, understanding their toxic effects on different aquatic organisms is essential. In the present study, we evaluated the toxicity of ZnO nanoparticles of 10 to 30 nm (ZnONPI) and 80 to 200 nm (ZnONPII), ZnO nanorods (width 80 nm, height 1.7 µm) attached to the support substrate (glass, ZnONRG) and not attached (ZnONRS), as well as Zn2+ ions at concentrations ranging from 0.5 to 100 mg/L. Toxicity was evaluated using the microalga Dunaliella salina, the brine shrimp Artemia salina, and the marine bacterium Bacillus cereus. The highest toxicity was observed for ZnONPs (median lethal concentration [LC50] ~15 mg/L) and Zn2+ ions (LC50 ~13 mg/L), whereas the lowest toxicity found for ZnO nanorods (ZnONRG LC50 ~60 mg/L; ZnONRS LC50 ~42 mg/L). The presence of the support substrate in case of ZnO nanorods reduced the associated toxicity to aquatic organisms. Smaller ZnONPs resulted in the highest Zn2+ ion dissolution among tested nanostructures. Different aquatic organisms responded differently to ZnO nanomaterials, with D. salina and B. cereus being more sensitive than A. salina. Toxicity of nanostructures increased with an increase of the dose and the time of exposure. Supported ZnO nanorods can be used as a low‐toxicity alternative for future antimicrobial and antifouling applications. Environ Toxicol Chem 2020;39:1343–1354. © 2020 SETAC

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Logarithmic Transformation is Essential for Statistical Analysis of Fungicide EC50 Values

Cited by 29 publications

References 25 publications

Demethylase Inhibitor Fungicide Resistance in Pyrenophora teres f. sp. teres Associated with Target Site Modification and Inducible Overexpression of Cyp51

Demethylase Inhibitor Fungicide Resistance in Pyrenophora teres f. sp. teres Associated with Target Site Modification and Inducible Overexpression of Cyp51

Parallel evolution of multiple mechanisms for demethylase inhibitor fungicide resistance in the barley pathogenPyrenophora teresf. sp.maculata

Toxicity of Different Zinc Oxide Nanomaterials at 3 Trophic Levels: Implications for Development of Low‐Toxicity Antifouling Agents

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