Identification and characterization of a fusarium head blight resistance gene TaACT in wheat QTL‐2DL

Abstract

SummaryFusarium head blight (FHB) resistance in wheat is considered to be polygenic in nature. Cell wall fortification is one of the best resistance mechanisms in wheat against Fusarium graminearum which causes FHB. Metabolomics approach in our study led to the identification of a wide array of resistance‐related (RR) metabolites, among which hydroxycinnamic acid amides (HCAAs), such as coumaroylagmatine and coumaroylputrescine, were the highest fold change RR metabolites in the rachis of a resistant near‐isogenic line (NIL‐R) upon F. graminearum infection. Placement of these metabolites in the secondary metabolic pathway led to the identification of a gene encoding agmatine coumaroyl transferase, herein referred to as TaACT, as a candidate gene. Based on wheat survey sequence, TaACT was located within a FHB quantitative trait loci on chromosome 2DL (FHB QTL‐2DL) between the flanking markers WMC245 and GWM608. Phylogenetic analysis suggested that TaACT shared closest phylogenetic relationship with an ACT ortholog in barley. Sequence analysis of TaACT in resistant and susceptible NILs, with contrasting levels of resistance to FHB, led to the identification of several single nucleotide polymorphisms (SNPs) and two inversions that may be important for gene function. Further, a role for TaACT in FHB resistance was functionally validated by virus‐induced gene silencing (VIGS) in wheat NIL‐R and based on complementation studies in Arabidopsis with act mutant background. The disease severity, fungal biomass and RR metabolite analysis confirmed TaACT as an important gene in wheat FHB QTL‐2DL, conferring resistance to F. graminearum.

Transcriptomics of cereal–Fusarium graminearum interactions: what we have learned so far

“…In conclusion, the recent cloning of Fhb1 and 2DL (Kage et al ., ; Rawat et al ., ) from wheat has shown that much can be learned about the processes involved in host resistance through the cloning of genes providing quantitative FHB resistance.…”

“…For instance, metabolomics studies conducted on NILs with and without the 2DL QTL showed that hydroxycinnamic acid amides (HCAs), such as coumaroylagmatine, associated with resistance, were differentially produced between the resistant and susceptible NILs. Subsequent genetic mapping, followed by functional analyses using VIGS and the complementation of the Arabidopsis act mutant, identified the TaACT gene encoding an agmatine coumaroyltransferase as the gene underlying the 2DL QTL (Kage et al, 2017), demonstrating the usefulness of undertaking combinatorial approaches (Fig. 2).…”

Silencing of copine genes confers common wheat enhanced resistance to powdery mildew

“…Virus-induced gene silencing (VIGS) is a useful strategy for the study of gene function in cereals. It uses a Barley stripe mosaic virus (BSMV)-based silencing system in monocot plants (Bennypaul et al, 2012;Holzberg et al, 2002), and has been successfully utilized in wheat gene function studies (Ahmed et al, 2017;Kage et al, 2017;Liu et al, 2016).…”

Perspectives on the specific targeting of Fusarium graminearum for the development of alternative head blight treatment approaches

“…All the phenolic acid and flavonoid compounds mentioned above exhibit strong antioxidant properties (Rice‐Evans et al ., ), which has been hypothesized to be the source of the strong down‐regulatory effect of ferulic acid and other phenolic compounds on Tri gene expression (Boutigny et al ., , ). Finally, it is notable that phenolic compounds have been found at high concentration in the silk of various resistant maize varieties (Reid et al ., ), wheat (Hamzehzarghani, ; Kumaraswamy et al ., ; Kage et al ., ) and barley (Bollina et al ., ; Kumaraswamy et al ., ).…”