title: Effect of Fungicide Applications on Monilinia fructicola Population Diversity and Transposon Movement.
abstract: In this study, we investigated whether fungicide-induced mutagenesis previously reported in Monilinia fructicola could accelerate genetic changes in field populations. Azoxystrobin and propiconazole were applied to nectarine trees at weekly intervals for approximately 3 months between bloom and harvest in both 2013 and 2014. Fungicides were applied at half-label rate to allow recovery of isolates and to increase chances of sublethal dose exposure. One block was left unsprayed as a control. In total, 608 single-spore isolates were obtained from blighted blossoms, cankers, and fruit to investigate phenotypic (fungicide resistance) and genotypic (simple-sequence repeat [SSR] loci and gene region) changes. In both years, populations from fungicide-treated and untreated fruit were not statistically different in haploid gene diversity (P = 0.775 for 2013 and P = 0.938 for 2014), allele number (P = 0.876 for 2013 and P = 0.406 for 2014), and effective allele number (P = 0.861 for 2013 and P = 0.814 for 2014). Isolates from blossoms and corresponding cankers of fungicide treatments revealed no changes in SSR analysis or evidence for induced Mftc1 transposon translocation. No indirect evidence for increased genetic diversity in the form of emergence of reduced sensitivity to azoxystrobin, propiconazole, iprodione, and cyprodinil was detected. High levels of population diversity in all treatments provided evidence for sexual recombination of this pathogen in the field, despite apparent absence of apothecia in the orchard. Our results indicate that fungicide-induced, genetic changes may not occur or not occur as readily in field populations as they do under continuous exposure to sublethal doses in vitro.
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Madeline E
authors.initials: ME
authors.lastname: Dowling
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Patricia K
authors.initials: PK
authors.lastname: Bryson
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Harriet G
authors.initials: HG
authors.lastname: Boatwright
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Wilson
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Fan
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Sydney E
authors.initials: SE
authors.lastname: Everhart
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Brannen
authors.affiliation: First, second, third, fourth, fifth, and eighth authors: Department of Agricultural and Environmental Sciences, Clemson University, Clemson, SC 29634; sixth author: Department of Plant Pathology, University of Nebraska, Lincoln 68583; and seventh author: Plant Pathology Department, University of Georgia, Athens 30602.
authors.forename: Guido
authors.initials: G
authors.lastname: Schnabel
mesh_terms: D001203:Ascomycota / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004251:DNA Transposable Elements / Q000235:genetics; D005638:Fruit / Q000382:microbiology; D005659:Fungicides, Industrial / Q000494:pharmacology*; D014644:Genetic Variation / Q000187:drug effects*; D005838:Genotype; D008689:Methacrylates / Q000494:pharmacology; D016296:Mutagenesis; D010935:Plant Diseases / Q000382:microbiology*; D000068239:Prunus persica / Q000382:microbiology*; D011743:Pyrimidines / Q000494:pharmacology; D000073739:Strobilurins; D014197:Trees; D014230:Triazoles / Q000494:pharmacology
chemical_list: D004251:DNA Transposable Elements; D005659:Fungicides, Industrial; D008689:Methacrylates; D011743:Pyrimidines; D000073739:Strobilurins; D014230:Triazoles; C045950:propiconazole; C108338:cyprodinil; C087670:azoxystrobin