Reduced sensitivity to azoxystrobin is stable in Monilinia fructicola isolates

Authors

  • Isabela Vescove Primiano University of São Paulo; ESALQ; Dept. of Plant Pathology and Nematology
  • Juan Pablo Edwards Molina University of São Paulo; ESALQ; Dept. of Plant Pathology and Nematology
  • Louise Larissa May De Mio Federal University of Paraná; Dept. of Crop Science
  • Natalia Aparecida Peres University of Florida; Institute of Food and Agricultural Sciences; Gulf Coast Research and Education Center
  • Lilian Amorim University of São Paulo; ESALQ; Dept. of Plant Pathology and Nematology

DOI:

https://doi.org/10.1590/1678-992x-2015-0469

Keywords:

Prunus, Quinone-outside inhibitor

Abstract

A shift towards declining azoxystrobin sensitivity has been previously documented in a collection of Brazilian Monilinia fructicola isolates, but information on the stability of this trait after in vitro sub-culturing is not available. In this study, one highly-sensitive isolate and two isolates with reduced sensitivity to azoxystrobin, not exhibiting point mutations at codons 129, 137 and 143 in the target gene of cytochrome b were used. Two independent experiments consisted of 10 weekly transfers of each strain in potato dextrose agar (PDA). Conidial production and germination were quantified in the initial culture and, again, after the third, sixth and tenth transfer. Measures of mycelial growth were obtained in colonies growing on PDA amended with azoxystrobin at 1 µg mL−1 and salicylhydroxamic acid at 100 µg mL−1. Data were normalized to mycelial growth rate after each of the 10 transfers. The colony diameter in the less sensitive isolates was stable across the transfers in the PDA amended with the fungicide. The conidial production and mycelial growth rate did not decrease in non-amended media either. Our results suggest that the trait of reduced sensitivity to azoxystrobin is stable under no selection pressure for azoxystrobin.

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Published

2017-04-01

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How to Cite

Reduced sensitivity to azoxystrobin is stable in Monilinia fructicola isolates. (2017). Scientia Agricola, 74(2), 169-173. https://doi.org/10.1590/1678-992x-2015-0469