Genotypic diversity and resistance to azoxystrobin of Cercospora beticola on processing table beet in New York

Vaghefi, Niloofar and Hay, Frank S. and Kikkert, Julie and Pethybridge, Sarah J. (2016) Genotypic diversity and resistance to azoxystrobin of Cercospora beticola on processing table beet in New York. Plant Disease, 100 (7). pp. 1466-1473. ISSN 0191-2917

Abstract

Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (QOI) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer QOI resistance in fungi. High allelic diversity (He = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC50) > 0.2 μg/ml. The G143A mutation, known to cause QOI resistance in C. beticola, was found in isolates with EC50 values between 0.207 and 19.397 μg/ml. A single isolate with an EC50 of 0.272 μg/ml carried the F129L mutation, known to be associated with low levels of QOI resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version cannot be displayed due to copyright restrictions.
Faculty / Department / School: No Faculty
Date Deposited: 22 Aug 2017 05:09
Last Modified: 22 Aug 2017 05:09
Uncontrolled Keywords: Cercospora beticola; beet; azoxzstrobin; resistence in fungi; genotypic diversity
Fields of Research : 06 Biological Sciences > 0607 Plant Biology > 060704 Plant Pathology
06 Biological Sciences > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences
Identification Number or DOI: 10.1094/PDIS-09-15-1014-RE
URI: http://eprints.usq.edu.au/id/eprint/32947

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