Transcriptomic characterization of two major Fusarium resistance quantitative trait loci (QTLs), Fhb1 and Qfhs.ifa‐5A, identifies novel candidate genes

Abstract

Fusarium head blight, caused by Fusarium graminearum, is a devastating disease of wheat. We developed near-isogenic lines (NILs) differing in the two strongest known F. graminearum resistance quantitative trait loci (QTLs), Qfhs.ndsu-3BS (also known as resistance gene Fhb1) and Qfhs.ifa-5A, which are located on the short arm of chromosome 3B and on chromosome 5A, respectively. These NILs showing different levels of resistance were used to identify transcripts that are changed significantly in a QTL-specific manner in response to the pathogen and between mock-inoculated samples. After inoculation with F. graminearum spores, 16 transcripts showed a significantly different response for Fhb1 and 352 for Qfhs.ifa-5A. Notably, we identified a lipid transfer protein which is constitutively at least 50-fold more abundant in plants carrying the resistant allele of Qfhs.ifa-5A. In addition to this candidate gene associated with Qfhs.ifa-5A, we identified a uridine diphosphate (UDP)-glycosyltransferase gene, designated TaUGT12887, exhibiting a positive difference in response to the pathogen in lines harbouring both QTLs relative to lines carrying only the Qfhs.ifa-5A resistance allele, suggesting Fhb1 dependence of this transcript. Yet, this dependence was observed only in the NIL with already higher basal resistance. The complete cDNA of TaUGT12887 was reconstituted from available wheat genomic sequences, and a synthetic recoded gene was expressed in a toxin-sensitive strain of Saccharomyces cerevisiae. This gene conferred deoxynivalenol resistance, albeit much weaker than that observed with the previously characterized barley HvUGT13248.

Resistance to Fusarium verticillioides and fumonisin accumulation in maize inbred lines involves an earlier and enhanced expression of lipoxygenase (LOX) genes

“…The defence responses of the S genotype to the same pathogen were assayed in previous works at early stage after inoculation, performing microarray and RNA-Seq analyses for gene expression profiles and through enzymatic assays (Lanubile et al, 2010;2012a, b, 2013. In this study, a different resistant line and a longer time course, with sampling at 3, 7, 14 and 21 days post inoculation (dpi), were considered.…”

A Brachypodium UDP-Glycosyltransferase Confers Root Tolerance to Deoxynivalenol and Resistance to Fusarium Infection

“…These enzymes mediate the transfer of glycosyl residues from nucleotide sugars to acceptor aglycones, thus regulating properties of the acceptors such as their bioactivity, water solubility, and transport within the cell and throughout the organism (Gachon et al, 2005 Poppenberger et al, 2003), barley (Hv13248; Schweiger et al, 2010;Shin et al, 2012), wheat (TaUGT3 [Lulin et al, 2010] and TaUGT12887 [Schweiger et al, 2013b]), and Brachypodium distachyon (Bradi5g03300; Schweiger et al, 2013a). Conjugation of DON into D3G by the corresponding UGTs was only shown in heterologous species, such as Saccharomyces cerevisiae (Schweiger et al, 2010(Schweiger et al, , 2013a(Schweiger et al, , 2013b, Arabidopsis (Poppenberger et al, 2003;Shin et al, 2012), or wheat (Li et al, 2015). In that most recent study, heterologous overexpression of the barley UGT gene Hv13248 in wheat varieties susceptible to FHB was shown to result in higher resistance in both greenhouses and field conditions (Li et al, 2015).…”

Deoxynivalenol resistance as a component of FHB resistance

“…A wheat UGT similar to DOGT1, TaUGT3, could enhance DON tolerance when expressed in Arabidopsis (Lulin et al 2010). Wheat UGT gene TaUGT12887 provided weak DON tolerance when expressed in a toxin sensitive yeast strain (Schweiger et al 2013b). Transgenic Arabidopsis lines expressing a barley UGT (HvUGT13248) showed enhanced tolerance to DON toxicity (Shin et al 2012).…”

“…Annong 8455. In a study conducted by Schweiger et al (2013b), DON induced the transcription of genes encoding UGT and glutathione-S-transferases (GSTs) in wheat carrying both Fhb1 and a FHB resistance QTL on chromosome 5A (DON independent). In a recent RNAseq study conducted by Hofstad et al (2016) on wheat near isogenic lines carrying QTL Fhb1, DON induced genes included those encoding CYP450s, GSTs, UGTs, an ABC transporter and an O-methyltransferase.…”

“…Ongoing studies are trying to delineate other orphan genes involved in wheat resistance to disease, including FHB disease. Genes associated with DON resistance and the DON response Walter et al 2008Walter et al , 2015Jia et al 2009;Schweiger et al 2013bSchweiger et al , 2016. The genes linked to Fhb1 are involved in numerous defence responses in plants, including pathogenesisrelated (PR) proteins, the synthesis of antimicrobial compounds, antioxidative stress responses, DON detoxification, cell morphogenesis and cell wall fortification (Walter and Doohan 2011;Foroud et al 2012;Schweiger et al 2016).…”