Biology subjects

Zulak, K. G.

Publications and source records attributed to Zulak, K. G..

2 recordsLinked to original sources

bioRxiv2025

Monitoring fungicide resistance frequencies -- a case study of barley net blotch

Decreased sensitivity to fungicides impacts the effectiveness of fungicide applications for managing plant disease. Knowledge of the frequency of decreased sensitivity in field populations is critical for evaluating risks for disease control. This study has applied a droplet digital PCR detection approach to assess pathogen populations and quantify the frequencies of alleles associated with decreased sensitivity to either demethylation inhibitor or succinate dehydrogenase inhibitor fungicides in Pyrenophora teres causing net blotch on barley in Western Australia. Pyrenophora teres f. maculata was the most frequent form of the pathogen in the sampled region. Frequencies of decreased fungicide sensitivity alleles varied, being as great as 92% for the PtTi insertion in the CYP51A promoter, 88% for C-S75 and 28% for L489-2. Impacts of cultivar selection and weed hosts on the presence and survival of decreased fungicide sensitivity were observed. Determining the dynamics of alleles within different field populations of P. teres provides an important perspective on the impact of fungicides, the fitness associated with decreased fungicide sensitivity alleles and the susceptibility of barley cultivars.

pathology↗

bioRxiv2023

Exploiting long read sequencing to detect azole fungicide resistance mutations in Pyrenophora teres using unique molecular identifiers

Resistance to fungicides is a global challenge as target proteins under selection can evolve rapidly, reducing fungicide efficacy. To manage resistance, detection technologies must be fast and flexible enough to cope with a rapidly increasing number of mutations. The most important agricultural fungicides are azoles that target the ergosterol biosynthetic enzyme sterol 14-demethylase (CYP51). Mutations associated with azole resistance in the Cyp51 promoter and coding sequence can co-occur in the same allele at different positions and codons, increasing the complexity of resistance detection. Resistance mutations arise rapidly and cannot be detected using traditional amplification-based methods if they are not known. To capture the complexity of azole resistance in two net blotch pathogens of barley we used the Oxford Nanopore MinION to sequence the promoter and coding sequence of Cyp51A. This approach detected all currently known mutations from biologically complex samples increasing the simplicity of resistance detection as multiple alleles can be profiled in a single assay. With the mobility and decreasing cost of long read sequencing, we demonstrate this approach is broadly applicable for characterizing resistance within known agrochemical target sites.

microbiology↗