Transcriptomics analysis of propiconazole-treated Cochliobolus sativus reveals new putative azole targets in the plant pathogen
Cochliobolus sativus (anamorph: Bipolaris sorokiniana) is a filamentous fungus from the class Dothideomycetes. It is a pathogen of cereals including wheat and barley, and causes foliar spot blotch, root rot, black point on grains, head blight, leaf blight, and seedling blight diseases. Annual yields of these economically important cereals are severely reduced due to this pathogen attack. Evolution of fungicide resistant pathogen strains, availability of a limited number of potent antifungal compounds, and their efficacy are the acute issues in field management of phytopathogenic fungi. Propiconazole is a widely used azole fungicide to control the disease in fields. The known targets of azoles are the demethylase enzymes involved in ergosterol biosynthesis. Nonetheless, azoles have multiple modes of action, some of which have not been explored yet. Identifying the off-target effects of fungicides by dissecting gene expression profiles in response to them can provide insights into their modes of action and possible mechanisms of fungicide resistance. Moreover it can also reveal additional targets for development of new fungicides. Hence, we analyzed the global gene expression profile of C. sativus on exposure to sub-lethal doses of propiconazole in a time series. The gene expression patterns were confirmed using quantitative reverse transcriptase PCR (qRT-PCR). This study revealed overexpression of target genes from the sterol biosynthesis pathway supporting the reported mode of resistance against azoles. In addition, some new potential targets have also been identified, which could be explored to develop new fungicides and plant protection strategies.
KeywordsBipolaris sorokiniana Cochliobolus sativus Fungicide resistance Propiconazole RNA-seq Transcriptomics analysis
ATP binding cassette
Counts per million
Differentially expressed genes
Effective concentration to give half maximal response
Fragments per kilobase million
Hours post treatment
Kyoto Encyclopedia of Genes and Genomes
Log2 fold change
National Center for Biotechnology Information
Potato dextrose agar
Quantitative reverse transcriptase polymerase chain reaction
DS acknowledges the Junior and Senior Research fellowships from the University Grants Commission (UGC), India. The authors thank Dr. Rajeev Kumar, Dept. of Agricultural Biotechnology & Molecular Biology, Dr. Rajendra Prasad Central Agricultural University, Pusa (India) for providing the D2 isolate of C. sativus and Dr. I.K. Kalappanwar, Dept. of Genetics and Plant Breeding, University of Agricultural Sciences, Dharwad (India) for help in microscopic identification of the pathogen. The Centre for Cellular and Molecular Platforms (C-CAMP), Bangalore (India) is acknowledged for RNA sequencing.
NK received financial support in the form of Council of Scientific and Industrial Research (CSIR), India (BSC 0117) and RP received financial support from Department of Biotechnology (DBT), India (GAP 304126).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
- Agarwal AK, Rogers PD, Baerson SR, Jacob MR, Barker KS, Cleary JD, Walker LA, Nagle DG, Clark AM (2003) Genome-wide expression profiling of the response to polyene, pyrimidine, azole, and echinocandin antifungal agents in Saccharomyces cerevisiae. J Biol Chem 278:34998–35015CrossRefPubMedGoogle Scholar
- Bolton MD, Ebert MK, Faino L, Rivera-Varas V, de Jonge R, Van de Peer Y, Thomma BP, Secor GA (2016) RNA-sequencing of Cercospora beticola DMI-sensitive and-resistant isolates after treatment with tetraconazole identifies common and contrasting pathway induction. Fungal Genet Biol 92:1–13CrossRefPubMedGoogle Scholar
- Dubin H, Ginkel Mv (1991) The status of wheat diseases and disease research in warmer areas. Wheat for the nontraditional warm areas: a proceedings of the International Conference July 29–August 3 1990 Foz do Iguaçu, Brazil. CIMMYT, pp 125–145Google Scholar
- Duveiller E, Gilchrist L (1994) Production constraints due to Bipolaris sorokiniana in wheat: current situation and future prospects. Wheat in Warm Area, Rice-Wheat Farming Systems Dinajpur (Bangladesh) 13–15 Feb 1993Google Scholar
- Hargrove TY, Friggeri L, Wawrzak Z, Qi A, Hoekstra WJ, Schotzinger RJ, York JD, Guengerich FP, Lepesheva GI (2017) Structural analyses of Candida albicans sterol 14 alpha-demethylase complexed with azole drugs address the molecular basis of azole-mediated inhibition of fungal sterol biosynthesis. Journal of Biological Chemistry:jbc. M117. 778308Google Scholar
- Mehta Y, McNab A (1998) Constraints on the integrated management of spot blotch of wheat. Helminthosporium Blight of Wheat: Spot Blotch and Tan Spot. pp. 18-27Google Scholar
- Oliveros JC (2007) VENNY. An interactive tool for comparing lists with Venn DiagramsGoogle Scholar
- Secor GA, Rivera VV (2012) Fungicide resistance assays for fungal plant pathogens. Plant Fungal Pathogens: Methods and Protocols:385–392Google Scholar
- Szklarczyk D, Franceschini A, Wyder S, Forslund K, Heller D, Huerta-Cepas J, Simonovic M, Roth A, Santos A, Tsafou KP (2014) STRING v10: protein–protein interaction networks, integrated over the tree of life. Nucleic Acids Research:gku1003Google Scholar
- Zhu N, Liu J, Yang J, Lin Y, Yang Y, Ji L, Li M, Yuan H (2016) Comparative analysis of the secretomes of Schizophyllum commune and other wood-decay basidiomycetes during solid-state fermentation reveals its unique lignocellulose-degrading enzyme system. Biotechnol Biofuels 9:42CrossRefPubMedPubMedCentralGoogle Scholar