Genetic insights into underground responses to Fusarium graminearum infection in wheat

Kai P Voss-Fels,Sven Gottwald,Wolfgang Friedt,Rod J Snowdon,Iulian Gabur,Lunwen Qian,Lee T Hickey,Christian Obermeier,Matthias Frisch,Christian R Werner,Stefan Kontowski

doi:10.1038/s41598-018-31544-w

Abstract

The ongoing global intensification of wheat production will likely be accompanied by a rising pressure of Fusarium diseases. While utmost attention was given to Fusarium head blight (FHB) belowground plant infections of the pathogen have largely been ignored. The current knowledge about the impact of soil borne Fusarium infection on plant performance and the underlying genetic mechanisms for resistance remain very limited. Here, we present the first large-scale investigation of Fusarium root rot (FRR) resistance using a diverse panel of 215 international wheat lines. We obtained data for a total of 21 resistance-related traits, including large-scale Real-time PCR experiments to quantify fungal spread. Association mapping and subsequent haplotype analyses discovered a number of highly conserved genomic regions associated with resistance, and revealed a significant effect of allele stacking on the stembase discoloration. Resistance alleles were accumulated in European winter wheat germplasm, implying indirect prior selection for improved FRR resistance in elite breeding programs. Our results give first insights into the genetic basis of FRR resistance in wheat and demonstrate how molecular parameters can successfully be explored in genomic prediction. Ongoing work will help to further improve our understanding of the complex interactions of genetic factors influencing FRR resistance.

Highlights

Global wheat production must be significantly increased in coming decades to meet future demands of the rapidly growing world population[1]
The focus in these studies was to investigate geographic occurrence of predominant pathogen species or physiological distribution of pathogen spread within the plant, but data generated from RT-PCR has not been used in genetic mapping yet
A major effect quantitative trait loci (QTL) associated with FCR resistance caused by F. pseudograminearum and F. graminearum was previously mapped on the long arm of chromosome 3B bi-parental mapping populations[25,26,27]

Summary

Introduction

Global wheat production must be significantly increased in coming decades to meet future demands of the rapidly growing world population[1]. Identified resistance loci for FHB and FCR did not co-locate in a QTL mapping study by Li et al.[10], whereas there were no major FHB resistance QTL detected in a mapping population carrying resistance to FCR11 This highlights the limited value of data accumulated from FHB research for resistance improvement of FCR and FRR. We present the first large-scale genome-wide association study (GWAS) of seedling resistance towards FRR caused by Fg. We phenotyped a diverse collection of 215 international hexaploid wheat lines in a comprehensive greenhouse screen after root infection with fungal spores. Using genome-wide single-nucleotide-polymorphism (SNP) data for haplotype analyses we identified conserved chromosome regions associated with resistance and provide first insights into the complex genetic architecture of FRR seedling resistance in wheat. Our findings demonstrate the potential to improve quantitative resistance via haplotype stacking and provide a valuable basis for further molecular validations and genomics-assisted breeding to improve FRR resistance in future wheat varieties

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Conclusion