Suppressed recombination and unique candidate genes in the divergent haplotype encoding Fhb1, a major Fusarium head blight resistance locus in wheat

Abstract

Key messageFine mapping and sequencing revealed 28 genes in the non-recombining haplotype containingFhb1. Of these, only a GDSL lipase gene shows a pathogen-dependent expression pattern.AbstractFhb1 is a prominent Fusarium head blight resistance locus of wheat, which has been successfully introgressed in adapted breeding material, where it confers a significant increase in overall resistance to the causal pathogen Fusarium graminearum and the fungal virulence factor and mycotoxin deoxynivalenol. The Fhb1 region has been resolved for the susceptible wheat reference genotype Chinese Spring, yet the causal gene itself has not been identified in resistant cultivars. Here, we report the establishment of a 1 Mb contig embracing Fhb1 in the donor line CM-82036. Sequencing revealed that the region of Fhb1 deviates from the Chinese Spring reference in DNA size and gene content, which explains the repressed recombination at the locus in the performed fine mapping. Differences in genes expression between near-isogenic lines segregating for Fhb1 challenged with F. graminearum or treated with mock were investigated in a time-course experiment by RNA sequencing. Several candidate genes were identified, including a pathogen-responsive GDSL lipase absent in susceptible lines. The sequence of the Fhb1 region, the resulting list of candidate genes, and near-diagnostic KASP markers for Fhb1 constitute a valuable resource for breeding and further studies aiming to identify the gene(s) responsible for F. graminearum and deoxynivalenol resistance.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-016-2727-x) contains supplementary material, which is available to authorized users.

Breeding strategies and advances in line selection for Fusarium head blight resistance in wheat

“…For Fhb1 the nearly diagnostic marker UMN10 (Liu et al 2008) is available, which is used worldwide in many wheat breeding programs for markerassisted introgression of Fhb1 (Buerstmayr et al 2009. Recently, UMN10 was complemented by a userfriendly KASP marker derived from the sequenced UMN10 PCR product (Schweiger et al 2016). For other resistance QTL markers flanking the QTL region are employed and for Fhb7, a major QTL derived from Thinopyrum ponticum, translocation lines with shortened alien segments and closely linked markers were developed (Guo et al 2015).…”

“…Recently the QTL region has been resolved for the highly resistant CIMMYT line CM-82036 showing substantial deviates from the Chinese Spring reference in size and gene content. Repressed recombination at the locus complicated fine-mapping and highlighted 28 putative candidate genes (Schweiger et al 2016). Of these, a gene encoding a chimeric lectin with agglutinin domains and a pore-forming toxin-like domain has been identified as the causal gene behind spreading resistance (type 2) by mutation analysis, gene silencing and transgenic overexpression.…”

QTL mapping of Fusarium head blight resistance in three related durum wheat populations

“…Near diagnostic markers for Fhb1 are available (Liu et al 2008; Schweiger et al 2016) and have been successfully implemented into applied wheat breeding using marker-assisted selection (Anderson et al 2007; Wilde et al 2007; Salameh et al 2011). Notwithstanding, the consequence of transferring this major QTL into tetraploid wheat has not been communicated until now.…”

Time‐course expression QTL‐atlas of the global transcriptional response of wheat to Fusarium graminearum

“…Nineteen and 21 eQTL at 30 hai and 50 hai map within a 3 cM interval including Fhb1 between markers Gwm389 and Barc133 (Table S4). None of these matched the 28 candidate genes located in the recently sequenced interval of Fhb1 (Schweiger et al ., ), because many of these comprise variety‐unique genes, are poorly expressed and/or are annotated as low confidence genes. Still, trans‐regulated eQTL may be implicated as downstream targets of the QTL activity.…”