Multiple Mutations and Overexpression in the <i>CYP51A</i> and <i>B</i> Genes Lead to Decreased Sensitivity of <i>Venturia effusa</i> to Tebuconazole

Multiple Mutations and Overexpression in the <i>CYP51A</i> and <i>B</i> Genes Lead to Decreased Sensitivity of <i>Venturia effusa</i> to Tebuconazole

Multiple demethylation-inhibiting (DMI) fungicides are used to control pecan scab, caused by <i>Venturia effusa</i>. To compare the efficacy of various DMI fungicides on <i>V. effusa</i>, field trials were conducted at multiple locations applying fungicides to individual peca...

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Bibliographic Details
Main Authors: Logan C. Moore, Timothy B. Brenneman, Sumyya Waliullah, Clive H. Bock, Md Emran Ali
Format: Article
Language:English
Published: MDPI AG 2022-01-01
Series:Current Issues in Molecular Biology
Subjects:
<i>V. effusa</i>
mutation
overexpression
pecan
DMI
resistance
Online Access:https://www.mdpi.com/1467-3045/44/2/47
Description
Summary:Multiple demethylation-inhibiting (DMI) fungicides are used to control pecan scab, caused by <i>Venturia effusa</i>. To compare the efficacy of various DMI fungicides on <i>V. effusa</i>, field trials were conducted at multiple locations applying fungicides to individual pecan terminals. In vitro assays were conducted to test the sensitivity of <i>V. effusa</i> isolates from multiple locations to various concentrations of tebuconazole. Both studies confirmed high levels of resistance to tebuconazole. To investigate the mechanism of resistance, two copies of the <i>CYP51</i> gene, <i>CYP51A</i> and <i>CYP51B</i>, of resistant and sensitive isolates were sequenced and scanned for mutations. In the <i>CYP51A</i> gene, mutation at codon 444 (G444D), and in the <i>CYP51B</i> gene, mutations at codon 357 (G357H) and 177 (I77T/I77L) were found in resistant isolates. Expression analysis of <i>CYP51A</i> and <i>CYP51B</i> revealed enhanced expression in the resistant isolates compared to the sensitive isolates. There were 3.0- and 1.9-fold increases in gene expression in the resistant isolates compared to the sensitive isolates for the <i>CYP51A</i> and <i>CYP51B</i> genes, respectively. Therefore, two potential mechanisms—multiple point mutations and gene over expression in the <i>CYP51</i> gene of <i>V. effusa</i> isolates—were revealed as likely reasons for the observed resistance in isolates of <i>V. effusa</i> to tebuconazole.
ISSN:1467-3037
1467-3045

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