Abstract
Detoxification of fusariotoxin is a type V Fusarium head blight (FHB) resistance and is considered a component of type II resistance, which is related to the spread of infection within spikes. Understanding this type of resistance is vital for FHB resistance, but to date, nothing is known about candidate genes that confer this resistance in rye due to scarce genomic resources. In this study, we generated a transcriptomic resource. The molecular response was mined through a comprehensive transcriptomic analysis of two rye hybrids differing in the build-up of fusariotoxin contents in grain upon pathogen infection. Gene mining identified candidate genes and pathways contributing to the detoxification of fusariotoxins in rye. Moreover, we found cis regulatory elements in the promoters of identified genes and linked them to transcription factors. In the fusariotoxin analysis, we found that grain from the Nordic seed rye hybrid “Helltop” accumulated 4 times higher concentrations of deoxynivalenol (DON), 9 times higher nivalenol (NIV), and 28 times higher of zearalenone (ZEN) than that of the hybrid “DH372” after artificial inoculation under field conditions. In the transcriptome analysis, we identified 6675 and 5151 differentially expressed genes (DEGs) in DH372 and Helltop, respectively, compared to non-inoculated control plants. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DEGs were associated with glycolysis and the mechanistic target of rapamycin (mTOR) signaling pathway in Helltop, whereas carbon fixation in photosynthesis organisms were represented in DH372. The gene ontology (GO) enrichment and gene set enrichment analysis (GSEA) of DEGs lead to identification of the metabolic and biosynthetic processes of peptides and amides in DH372, whereas photosynthesis, negative regulation of catalytic activity, and protein-chromophore linkage were the significant pathways in Helltop. In the process of gene mining, we found four genes that were known to be involved in FHB resistance in wheat and that were differentially expressed after infection only in DH372 but not in Helltop. Based on our results, we assume that DH372 employed a specific response to pathogen infection that led to detoxification of fusariotoxin and prevented their accumulation in grain. Our results indicate that DH372 might resist the accumulation of fusariotoxin through activation of the glycolysis and drug metabolism via cytochrome P450. The identified genes in DH372 might be regulated by the WRKY family transcription factors as associated cis regulatory elements found in the in silico analysis. The results of this study will help rye breeders to develop strategies against type V FHB.
Highlights
Fusarium head blight (FHB) is a devastating disease of cereals and is caused by trichothecene-producing pathogens belong to Fusarium spp. [1,2]
The transcriptomics data generated in this study will be a valuable asset to enhance overall omics resources for rye, keeping in view that there is not a single study in rye aiming to decipher FHB resistance through utilizing transcriptomic profiling
A putative gene network underlying the molecular response in two rye hybrids with differential accumulation of mycotoxin was proposed
Summary
Fusarium head blight (FHB) is a devastating disease of cereals and is caused by trichothecene-producing pathogens belong to Fusarium spp. [1,2]. FHB led to accumulation of high content of mycotoxins that contaminate the grain and, when ingested, can adversely affect livestock and human health [6,7]. Due to their acute toxicity to human and animals, several countries have put strict regulation on the permissible level of fusariotoxins in grains. Fusariotoxins such as deoxynivalenol act as a virulence factor for Fusarium, facilitating disease spread within spikes [8]. A number of genes such as glycosyltransferases, ATP-binding cassette transporters (ABC) transporters, and cytochrome P450s have been known to contribute FHB resistance through detoxification of fusariotoxins [16]
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