Abstract
BackgroundFusarium head blight (FHB) caused by Fusarium graminearum Schwabe is one of the most prevalent diseases of wheat (Triticum aestivum L.) and other small grain cereals. Resistance against the fungus is quantitative and more than 100 quantitative trait loci (QTL) have been described. Two well-validated and highly reproducible QTL, Fhb1 and Qfhs.ifa-5A have been widely investigated, but to date the underlying genes have not been identified.ResultsWe have investigated a gene co-expression network activated in response to F. graminearum using RNA-seq data from near-isogenic lines, harboring either the resistant or the susceptible allele for Fhb1 and Qfhs.ifa-5A. The network identified pathogen-responsive modules, which were enriched for differentially expressed genes between genotypes or different time points after inoculation with the pathogen. Central gene analysis identified transcripts associated with either QTL within the network. Moreover, we present a detailed gene expression analysis of four gene families (glucanases, NBS-LRR, WRKY transcription factors and UDP-glycosyltransferases), which take prominent roles in the pathogen response.ConclusionsA combination of a network-driven approach and differential gene expression analysis identified genes and pathways associated with Fhb1 and Qfhs.ifa-5A. We find G-protein coupled receptor kinases and biosynthesis genes for jasmonate and ethylene earlier induced for Fhb1. Similarly, we find genes involved in the biosynthesis and metabolism of riboflavin more abundant for Qfhs.ifa-5A.
Highlights
Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe is one of the most prevalent diseases of wheat (Triticum aestivum L.) and other small grain cereals
CM-82036 encodes for multiple minor effect resistance quantitative trait loci (QTL), which provide the line with a significantly higher level of resistance when compared to a near-isogenic line stacking both Fhb1 and Qfhs.ifa-5A resistance alleles in a susceptible background [10,14]
The lines comprised a set of four near-isogenic lines (NILs) that harbor either of the F. graminearum-resistance QTL Fhb1 (NIL2, moderately resistant) or Qfhs.ifa-5A (NIL3, moderately resistant), both of these QTL (NIL1, resistant) or none of them (NIL4, susceptible) in the genetic background of the F. graminearum susceptible German spring wheat cultivar Remus
Summary
Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe is one of the most prevalent diseases of wheat (Triticum aestivum L.) and other small grain cereals. Two well-validated and highly reproducible QTL, Fhb and Qfhs.ifa-5A have been widely investigated, but to date the underlying genes have not been identified. A large body of publications aiming towards genetic mapping of resistance genes against F. graminearum has been published in the last 14 years and so far over 100 quantitative trait loci (QTL) have been described to contribute to resistance [7]. Recent years have seen multiple transcriptomic and proteomic studies investigating the F. graminearum/wheatinteraction, which have helped developing an understanding of the general response against the fungus (reviewed in [2]), but these did not lead to the identification of QTLrelated resistance genes so far
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