Metabolic biomarker panels of response to Fusarium head blight infection in different wheat varieties

Metabolic changes in spikelets of wheat varieties FL62R1, Stettler, Muchmore and Sumai3 following Fusarium graminearum infection were explored using NMR analysis. Extensive 1D and 2D 1H NMR measurements provided information for detailed metabolite assignment and quantification leading to possible metabolic markers discriminating resistance level in wheat subtypes. In addition, metabolic changes that are observed in all studied varieties as well as wheat variety specific changes have been determined and discussed. A new method for metabolite quantification from NMR data that automatically aligns spectra of standards and samples prior to quantification using multivariate linear regression optimization of spectra of assigned metabolites to samples\u2019 1D spectra is described and utilized. Fusarium infection-induced metabolic changes in different wheat varieties are discussed in the context of metabolic network and resistance.Peer reviewed: YesNRC publication: Ye

PCA of 1D 1H NMR spectra for four wheat varieties at different time points.

<p>A. Analysis of profiles for each wheat type separately showing changes in metabolic profile at 0, 48 and 96 hpi. B. Analysis of metabolic profile differences between wheat varieties at different time point.</p

Metabolic Biomarker Panels of Response to Fusarium Head Blight Infection in Different Wheat Varieties - Fig 5

<p>A. He at map representation of hierarchically clustered quantitative metabolic data for 60 metabolites assigned from 2D spectra and quantified in all 1D 1H NMR spectra. The obtained values are shown following scaling of spectra but without any scaling or normalization of metabolite concentrations. B. Significant analysis of microarray (SAM) analysis of major concentration changes between control and 2 treated groups separately in four wheat subtypes following sample and metabolite scaling.</p

Spectra of standards used in the quantification analysis.

<p>Spectra of standards used in the quantification analysis.</p

Disease severity levels in four wheat varieties: Sumai3, FL62R1, Stettler, andMuchmore.

<p>The percentage of infected rachis nodes per headwas scored at the time points indicated. Two heads per plant and 20 plants per variety, for a total of 40 heads, were examined for each variety at each time point.Values represent means ± standard error. A one-way ANOVA of data were performed in each time point at α = 0.05 to determine significance among different varieties. Histograms with different letters are statistically different.</p

Schematic overview of metabolites measured in the presented experiment and their significance in resistance response through metabolism.

<p>Histograms indicate logarithms of concentration change at 48hpi (red) and 96hpi (blue) relative to the control for (in order): FL62R1, Muchmore, Stettler and Sumai3. In plot zero value (no change from control) is shown with the thick line. Positive values indicate concentration increased and negative concentration decrease relative to the control values. A. Metabolites involved in cell wall development. B. Phenylpropanoid Pathway (PhPrP) resulting in production of active phenolic phytochemical known as important factors in plant resistance to pathogens. C. Spermine biosynthesis pathway. Spermine has been hypothesized to act as an inducer of PR proteins and as a trigger for caspase-like activity (Crampton et al., 2009); D. gamma-Aminobutyric acid (GABA)–shunt block bypassing two steps in tricarboxylic acid (TCA) cycle and leading to production of GABA from glutamate; E. Amino acid metabolism; F. Biosynthesis of choline derivatives. More detail information including all metabolites involved in the shown processes is provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0153642#pone.0153642.s005" target="_blank">S5 Fig</a>. Hv acid—homovanillic acid; PhPrP—Phenylpropanoid Pathway; SAR—systemic acquired resistance; PPP—Pentose phosphate pathway.G6P –glucose 6-phosphate; 3PGA– 3-phosphoglyceric acid; PEP—phosphoenolpyruvic acid; G1P –glucose 1-phosphate; galactose1P –galactose 1-phosphate; glycerol-3P- glycerol 3-phosphate; hv acid—homovanilic acid.</p

PCA of 1D 1H NMR spectra for four wheat varieties at different time points showing major profile differences between individual time points for each wheat type.

<p>PCA of 1D 1H NMR spectra for four wheat varieties at different time points showing major profile differences between individual time points for each wheat type.</p

Synchrotron based phase contrast X-ray imaging combined with FTIR spectroscopy reveals structural and biomolecular differences in spikelets play a significant role in resistance to Fusarium in wheat

Background: Fusarium head blight (FHB), a scab principally caused by Schw., is a serious disease of wheat. The purpose of this study is to evaluate the potential of combining synchrotron based phase contrast X-ray imaging (PCI) with Fourier Transform mid infrared (FTIR) spectroscopy to understand the mechanisms of resistance to FHB by resistant wheat cultivars. Our hypothesis is that structural and biochemical differences between resistant and susceptible cultivars play a significant role in developing resistance to FHB. Results: Synchrotron based PCI images and FTIR absorption spectra (4000-800 cm) of the floret and rachis from Fusarium-damaged and undamaged spikes of the resistant cultivar 'Sumai3', tolerant cultivar 'FL62R1', and susceptible cultivar 'Muchmore' were collected and analyzed. The PCI images show significant differences between infected and non-infected florets and rachises of different wheat cultivars. However, no pronounced difference between non-inoculated resistant and susceptible cultivar in terms of floret structures could be determined due to the complexity of the internal structures. The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars. The changes in absorption wavenumbers following pathogenic infection were mostly in the spectral range from 1800-800 cm. The Principal Component Analysis (PCA) was also used to determine the significant chemical changes inside floret and rachis when exposed to the FHB disease stress to understand the plant response mechanism. In the floret and rachis samples, PCA of FTIR spectra revealed differences in cell wall related polysaccharides. In the florets, absorption peaks for Amide I, cellulose, hemicellulose and pectin were affected by the pathogenic fungus. In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra. Amide II and lignin absorption peaks, persistent in the rachis of Sumai3, together with increased peak shift at 1245 cm after infection with FHB may be a marker for stress response in which the cell wall compounds related to pathways for lignification are increased. Conclusions: Synchrotron based PCI combined with FTIR spectroscopy show promising results related to FHB in wheat. The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress.Peer reviewed: YesNRC publication: Ye

Pearson correlation analysis of metabolic concentration changes over three time points in different wheat varieties.

<p>Network shows both positive and negative correlation of over 95%.</p