Analysis of the CYP51 gene and encoded protein in propiconazole-resistant isolates of Mycosphaerella fijiensis.
BACKGROUND
Mycosphaerella fijiensis Morelet causes black sigatoka, the most important disease in bananas and plantains. Disease control is mainly through the application of systemic fungicides, including sterol demethylation inhibitors (DMIs). Their intensive use has favoured the appearance of resistant strains. However, no studies have been published on the possible resistance mechanisms.


RESULTS
In this work, the CYP51 gene was isolated and sequenced in 11 M. fijiensis strains that had shown different degrees of in vitro sensitivity to propiconazole, one of the most widely used DMI fungicides. Six mutations that could be related to the loss in sensitivity to this fungicide were found: Y136F, A313G, Y461D, Y463D, Y463H and Y463N. The mutations were analysed using a homology model of the protein that was constructed from the crystallographic structure of Mycobacterium tuberculosis (Zoff.) Lehmann & Neumann. Additionally, gene expression was determined in 13 M. fijiensis strains through quantitative analysis of products obtained by RT-PCR.


CONCLUSIONS
Several changes in the sequence of the gene encoding sterol 14alpha-demethylase were found that have been described in other fungi as being correlated with resistance to azole fungicides. No correlation was found between gene expression and propiconazole resistance.
Cañas-Gutiérrez
Gloria P
GP
Unidad de Biotecnología Vegetal, Corporación para Investigaciones Biológicas UNALMED-CIB, Carrera 72 A # 78 B-141, Medellín, Colombia.
Angarita-Velásquez
Mónica J
MJ
Restrepo-Flórez
Juan M
JM
Rodríguez
Paola
P
Moreno
Claudia X
CX
Arango
Rafael
R
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics* / Q000502:physiology; D020134:Catalytic Domain; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics*; D025141:Drug Resistance, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017385:Sequence Homology; D058886:Sterol 14-Demethylase; D014230:Triazoles / Q000494:pharmacology*
D005656:Fungal Proteins; D014230:Triazoles; C045950:propiconazole; D003577:Cytochrome P-450 Enzyme System; D058886:Sterol 14-Demethylase