W. Schweiger, B. Steiner, S. Vautrin, T. Nussbaumer, G. Siegwart, M. Zamini, F. Jungreithmeier, V. Gratl, M. Lemmens,

 K. F. X. Mayer, H. Bérgès, G. Adam, H. Buerstmayr

Theoretical and Applied Genetics August 2016, Volume 129, Issue 8, pp 1607–1623

Key message

Fine mapping and sequencing revealed 28 genes in the non-recombining haplotype containing Fhb1 . Of these, only a GDSL lipase gene shows a pathogen-dependent expression pattern.

Abstract

Fhb1 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.

See http://link.springer.com/article/10.1007/s00122-016-2727-x

Fig. 1

Reconstruction of the Fhb1 region in CM-82036. a Sequenced BACs bridge a distance of 1.027 kb including flanking markers sts32 and sts189 and near-diagnostic marker UMN10. Arrows indicate positions and orientations of annotated genes. Light gray arrows relate to low confidence gene models. b Dot plot analysis comparing the sequenced Fhb1 contig to the colinear segment of the published sequence of Chinese Spring (ctg0954b). c Comparison of gene content between CM-82036 and Chinese Spring. Regions with highly similar genes are shaded in gray. Genes with homology <80 % are indicated by dashed lines