A Quantitative Proteomics View on the Function of Qfhb1, a Major QTL for Fusarium Head Blight Resistance in Wheat.

Moustafa Eldakak,Karl Glover,Yongbin Zhuang,Yang Yen,Jai Rohila,Aayudh Das

doi:10.3390/pathogens7030058

Abstract

Fusarium head blight (FHB) is a highly detrimental disease of wheat. A quantitative trait locus for FHB resistance, Qfhb1, is the most utilized source of resistance in wheat-breeding programs, but very little is known about its resistance mechanism. In this study, we elucidated a prospective FHB resistance mechanism by investigating the proteomic signatures of Qfhb1 in a pair of contrasting wheat near-isogenic lines (NIL) after 24 h of inoculation of wheat florets by Fusarium graminearum. Statistical comparisons of the abundances of protein spots on the 2D-DIGE gels of contrasting NILs (fhb1+ NIL = Qfhb1 present; fhb1- NIL = Qfhb1 absent) enabled us to select 80 high-ranking differentially accumulated protein (DAP) spots. An additional evaluation confirmed that the DAP spots were specific to the spikelet from fhb1- NIL (50 spots), and fhb1+ NIL (seven spots). The proteomic data also suggest that the absence of Qfhb1 makes the fhb1- NIL vulnerable to Fusarium attack by constitutively impairing several mechanisms including sucrose homeostasis by enhancing starch synthesis from sucrose. In the absence of Qfhb1, Fusarium inoculations severely damaged photosynthetic machinery; altered the metabolism of carbohydrates, nitrogen and phenylpropanoids; disrupted the balance of proton gradients across relevant membranes; disturbed the homeostasis of many important signaling molecules induced the mobility of cellular repair; and reduced translational activities. These changes in the fhb1- NIL led to strong defense responses centered on the hypersensitive response (HSR), resulting in infected cells suicide and the consequent initiation of FHB development. Therefore, the results of this study suggest that Qfhb1 largely functions to either alleviate HSR or to manipulate the host cells to not respond to Fusarium infection.

Highlights

Fusarium head blight (FHB; caused by ascomycetous fungi Fusarium species) is a common fungal disease of wheat (Triticum aestivum L.) and many other cereal crops in both semitropical and temperate regions worldwide
The 2D-DIGE technology used in this study enabled us to simultaneously run two, contrasting protein samples on a single gel, eliminating the major random errors usually encountered in an ordinary 2DE assay, for which each sample is run on a separate gel
Any differentially accumulated proteins between the near-isogenic lines (NIL) pair or the treatments within a NIL should be either encoded or controlled by genes located within this molecular marker interval and provide key information about the molecular mechanism of the FHB resistance presented by Qfhb1

Summary

Introduction

Fusarium head blight (FHB; caused by ascomycetous fungi Fusarium species) is a common fungal disease of wheat (Triticum aestivum L.) and many other cereal crops in both semitropical and temperate regions worldwide. It can cause devastating reductions in both grain yield and quality. While many Fusarium fungi can cause FHB, F. graminearum is the predominant FHB pathogen in North America and many other places across the world [3]. Hundreds of Type II resistance QTLs have been reported across the wheat genome.

Methods

Results

Conclusion