title: Real-time PCR to study the effect of timing and persistence of fungicide application and wheat varietal resistance on Mycosphaerella graminicola and its sterol 14α-demethylation-inhibitor-resistant genotypes.
abstract: BACKGROUND
  Sterol 14α-demethylase inhibitors (DMIs) have been widely used for more than 20 years against wheat Septoria leaf blotch. However, resistance towards DMIs has increased in recent years. The objective of this study was to evaluate the effect of fungicide timing and persistence and wheat resistance varietal on Mycosphaerella graminicola and its DMI-resistant genotypes.
  
  
  RESULTS
  Using qPCR, M. graminicola was detected 2 weeks later in the resistant cultivar than in the susceptible cultivar. A high proportion of DMI-moderate resistant genotypes (≥94%) was found in all samples, with an average of 74.2, 0.1 and 19.7% for R6, R7- and R7+ genotypes, respectively. Distribution of DMI-resistant genotypes was neither affected by different wheat cultivars nor by analysis dates. Electron microscopy coupled with qPCR analysis showed that the DMI fungicide prothioconazole had a significant inhibitive effect against spore germination and post-germination. However, the preventive treatment was the most effective, but it was affected strongly by fungicide persistence.
  
  
  CONCLUSIONS
  Preventive fungicide applications are more effective against Septoria leaf blotch than the curative treatments, so persistence and wheat varietal resistance should be taken into account in the management of this disease. It would seem that none of the studied factors affect the frequency of DMI-resistant genotypes.
authors: Platform of Biotechnology and Plant Pathology, Institut Polytechnique LaSalle Beauvais, 19 rue Pierre Waguet, BP 30313, 60026, Beauvais Cedex, France.
authors: Sameh
authors: S
authors: Selim
authors: Céline
authors: C
authors: Roisin-Fichter
authors: Jean-Baptiste
authors: JB
authors: Andry
authors: Boris
authors: B
authors: Bogdanow
authors: Renée
authors: R
authors: Sambou
mesh_terms: D058888:14-alpha Demethylase Inhibitors / Q000494:pharmacology*; D001203:Ascomycota / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D025141:Drug Resistance, Fungal; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005659:Fungicides, Industrial / Q000494:pharmacology*; D005838:Genotype; D010935:Plant Diseases / Q000382:microbiology*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D058886:Sterol 14-Demethylase / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000382:microbiology*
chemical_list: D058888:14-alpha Demethylase Inhibitors; D005656:Fungal Proteins; D005659:Fungicides, Industrial; D058886:Sterol 14-Demethylase
keywords: DMI-resistant genotypes; Mycosphaerella graminicola; epidemiology; fungicide efficiency; real-time PCR; wheat varietal resistance