Lack of an Intron in Cytochrome b and Overexpression of Sterol 14 alpha-Demethylase Indicate a Potential Risk for QoI and DMI Resistance Development in Neophysopella spp. on Grapes

A - Papers appearing in refereed journals

Santos, R. F., Amorium, L., Wood, A. K. M., Bibiano, L. B. J. and Fraaije, B. A. 2021. Lack of an Intron in Cytochrome b and Overexpression of Sterol 14 alpha-Demethylase Indicate a Potential Risk for QoI and DMI Resistance Development in Neophysopella spp. on Grapes. Phytopathology. 111 (10), pp. 1726-1734. https://doi.org/10.1094/PHYTO-11-20-0514-R

AuthorsSantos, R. F., Amorium, L., Wood, A. K. M., Bibiano, L. B. J. and Fraaije, B. A.
Abstract

Asian grapevine leaf rust, caused by Neophysopella meliosmae-myrianthae and N. tropicalis, is often controlled by quinone outside inhibitor (QoI) and demethylation inhibitor (DMI) fungicides in Brazil. Here, we evaluated the sensitivity of 55 Neophysopella spp. isolates to pyraclostrobin (QoI) and tebuconazole (DMI). To elucidate the resistance mechanisms, we analyzed the sequences of the cytochrome b (CYTB) and cytochrome P450 sterol 14 alpha-demethylase (CYP51) target proteins of QoI and DMI fungicides, respectively. The CYP51 expression levels were also determined in a selection of isolates. In leaf disc assays, the mean 50% effective concentration (EC50) value for pyraclostrobin was about 0.040 mu g/ml for both species. CYTB sequences were identical among all 55 isolates, which did not contain an intron immediately after codon 143. No amino acid substitution was identified at codons 129, 137, and 143. The mean EC50 value for tebuconazole was 0.62 mu g/ml for N. tropicalis and 0.46 mu g/ml for N. meliosmae-myrianthae, and no CYP51 sequence variation was identified among isolates of the same species. However, five N. meliosmae-myrianthae isolates grew on leaf discs treated at 10 mu g/ml tebuconazole, and these were further exposed to tebuconazole selection pressure. Tebuconazole-adapted laboratory isolates of N. meliosmae-myrianthae showed an eight- to 25-fold increase in resistance after four rounds of selection that was not associated with CYP51 target alterations. In comparison with sensitive isolates, CYP51 expression was induced in the presence of tebuconazole in three out of four tebuconazole-adapted isolates tested. These results suggest a potential risk for QoI and DMI resistance development in Neophysopella spp.

KeywordsAntimicrobial or fungicide resistance; Asian grapevine leaf rust; CYP51 overexpression; Ecology and epidemiology; Fungicide resistance; Intron-less cytochrome b; Risk assessment; Molecular
Year of Publication2021
JournalPhytopathology
Journal citation111 (10), pp. 1726-1734
Digital Object Identifier (DOI)https://doi.org/10.1094/PHYTO-11-20-0514-R
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDesigning Future Wheat (DFW) [ISPG]
Publisher's version
Output statusPublished
Publication dates
Online03 Nov 2021
Publication process dates
Accepted01 Oct 2021
PublisherAmerican Phytopathological Society (APS)
ISSN0031-949X

Permalink - https://repository.rothamsted.ac.uk/item/98782/lack-of-an-intron-in-cytochrome-b-and-overexpression-of-sterol-14-alpha-demethylase-indicate-a-potential-risk-for-qoi-and-dmi-resistance-development-in-neophysopella-spp-on-grapes

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